WO2011162051A1 - Communication system, communication apparatus and communication method - Google Patents

Abstract

There are included a plurality of mapping units to which a plurality of sets of data signal sequences related to the same data signal sequence are input via the respective ones of spectrum cyclic shift units and which place the input data signal sequences on the frequency axis and output the placed data signal sequences as transport frequency spectra; an allocation information acquiring unit that controls, based on allocation information, the plurality of mapping units to arrange the data signal sequences on the frequency axis and to cause the arranged data signal sequences to partially overlap; the spectrum cyclic shift units that shift the input data signal sequences by the cyclic shift amounts under control of a shift amount determining unit, thereby causing the partially overlapping data signals to become the same for output; and a plurality of transmission antennas via which the transport frequency spectra output by the plurality of mapping units are transmitted.

Description

COMMUNICATION SYSTEM, COMMUNICATION DEVICE, AND COMMUNICATION METHOD

The present invention relates to a communication system, a communication apparatus, and a communication method.
This application claims priority based on Japanese Patent Application No. 2010-145691 filed in Japan on June 25, 2010, the contents of which are incorporated herein by reference.

Communication systems, especially mobile phone wireless communication systems, continue to develop as high-speed and large-capacity communication systems. LTE (Long Term Evolution, 3.9G radio access technology), a wireless communication standard of 3GPP (3rd Generation Partnership Project), and LTE-A (LTE-Advanced) In the evolution of LTE, as a downlink (wireless communication line from base station to terminal) transmission method, it has strong resistance to frequency selective fading, and MIMO (Multiple-Input-Multiple-Output, Multiple Input / Multiple Output) transmission OFDMA (Orthogonal Frequency Division Multiple Access, orthogonal frequency division multiple access) is used. On the other hand, in the uplink (wireless communication line from the terminal to the base station) transmission method, the cost and scale of the terminal are important.

However, in multi-carrier transmission such as OFDMA and MC-CDMA (Multi-Carrier Code Division Multiple Access), the terminal receives the PAPR (Peak to Average Power Ratio), peak-to-average power ratio of the transmission signal. ) Is high and requires a power amplifier with a wide linear region, and is not suitable for uplink transmission. That is, single carrier transmission with a low PAPR is desirable in order to maintain wide coverage in the uplink (communication coverage range, for example, distance to the base station). Also in LTE, SC-FDMA (Single Carrier Frequency Division Multiple Access, single-wave frequency division multiple access, also called DFT-S-OFDM), which is single carrier transmission, is employed for the uplink.

Further, there is a transmission antenna diversity (sometimes referred to as “transmission diversity”) as a method for achieving a wide coverage. In transmission diversity, for example, considering uplink, a signal subjected to different signal processing is transmitted from a plurality of antennas of a transmission device (in this case, a transmission part of a terminal), and a reception device (this In this case, the transmission antenna diversity gain can be obtained by receiving with the receiving antenna of the base station. Transmission diversity is based on open-loop transmission diversity in which the transmission device transmits without using the propagation path information of the propagation path between the reception apparatus and the propagation path information of the propagation path between the transmission apparatus and the reception apparatus. It is roughly classified into closed-loop transmission diversity that performs transmission processing.

Open-loop transmission diversity includes space-time block coding STBC (Space Time Block Coding), space frequency block coding SFBC (Space Frequency Block Coding), cyclic delay diversity CDD (Cyclic Delay Diversity), and the like. The closed-loop transmission diversity includes antenna selection transmission diversity, maximum ratio transmission / reception antenna diversity, and the like. In the uplink of LTE-A using this closed-loop transmission diversity, it is based on the code book (code table) described in Non-Patent Document 1. Precoding is to be adopted. In precoding, the transmission device transmits the signal transmitted from each of the transmission antennas by rotating the phase of the transmission signal so that the signals transmitted from the plurality of transmission antennas of the transmission device are received in phase by the reception device. The reception power at can be increased.

In addition, a plurality of antennas possessed by a transmission apparatus in a wireless communication system are not only used for improving communication quality by transmission diversity, but by transmitting independent signals from each antenna at the same time and the same frequency, It is also used as spatial multiplexing transmission that can improve In spatial multiplexing transmission, the number of signals transmitted simultaneously is called the number of streams, the number of ranks, or the number of layers. Signals transmitted from each antenna are separated by signal separation processing such as spatial filtering and maximum likelihood detection MLD (Maximum Likelihood Detection) in the receiving apparatus. In addition, since the frequency with good propagation path characteristics is different for each transmission antenna, Patent Document 1 and Japanese Patent Laid-Open No. 2003-26083 and the method for performing transmission with different frequency arrangements (sometimes referred to as “assignment” or “mapping”) for each transmission antenna. It is described in Patent Document 2. By allowing the use of different frequency arrangements for each transmission antenna, it is possible to perform communication by selecting a frequency with a high gain for each transmission antenna, thereby enabling spatial multiplexing transmission with high reception quality. .

JP 2008-199598 A International Publication No. 2009/022709

In Patent Literature 1 and Patent Literature 2, although different frequency assignments are allowed in each transmission antenna of the transmission device, since the same data could not be transmitted from each transmission antenna, each transmission antenna was received by transmission diversity. It could not be used to improve quality. Each embodiment of the present invention solves this point.

(1) The present invention has been made to solve the above-described problems, and the communication apparatus according to the present invention includes a plurality of data signal sequences related to the same data signal sequence, at least a part of which is a spectrum. A plurality of mapping units that are input via a cyclic shift unit, wherein the input data signal sequence is arranged on a frequency axis, and a plurality of mapping units that output the arranged data signal sequence as a transmission frequency spectrum; An allocation information acquisition unit that controls the plurality of mapping units based on allocation information to arrange the data signal sequence on the frequency axis and controls the data signal sequences so as to partially overlap with each other, and the allocation information acquisition A cyclic shift amount determining unit that determines a cyclic shift amount based on the control of a unit, and the spectrum cyclic shift unit, the input data signal sequence of the shift amount determining unit Receiving the control, shifting the cyclic shift amount, outputting the partially overlapped data signals so as to be the same, and transmitting the transmission frequency spectrum output from the plurality of mapping units at a radio frequency A plurality of transmitting antennas.
(2) Moreover, the communication apparatus of the present invention is the communication apparatus described above, wherein the plurality of sets of data signal sequences are all input to the mapping unit via a spectrum cyclic shift unit.
(3) The communication device according to the present invention is the communication device described above, wherein the data signal sequence is directly input to the mapping unit by changing the amplitude and / or phase of the data signal of the data signal sequence. Or a precoding unit that inputs to the mapping unit via the spectral cyclic shift unit.
(4) Moreover, the communication apparatus of this invention is the above-mentioned communication apparatus, Comprising: The said spectrum cyclic shift part performs cyclic shift on the basis of the spectrum arrangement | positioning in the specific thing of these transmission antennas. It is characterized by.
(5) Moreover, the communication apparatus of this invention is the above-mentioned communication apparatus, Comprising: The said spectrum cyclic shift part performs cyclic shift on the basis of the index of the said transmission frequency spectrum, It is characterized by the above-mentioned.
(6) The present invention has been made to solve the above-described problems, and a communication system according to the present invention includes the communication device according to (1) or (2), one or more receiving antennas, An equalization unit that performs equalization using SIMO weights in the case where there is no interference for each transmission frequency spectrum from the receiving antenna, and a second communication device comprising: A data signal is transmitted / received to / from the second communication device.
(7) The present invention has been made to solve the above-described problems, and the communication method of the present invention provides a plurality of sets of data signal sequences related to the same data signal sequence, and the plurality of sets of data signal sequences. Each of the data signals is changed in amplitude, phase, or both, and the plurality of changed data signal sequences are subjected to cyclic shift, and the plurality of sets of data signal sequences subjected to the cyclic shift are converted into frequency axes. A plurality of sets of transmission frequency spectrums arranged on the frequency axis in such a manner that a part of the plurality of sets of data signal sequences overlaps and the overlapping data signals are the same. It transmits by the radio frequency from the transmission antenna of this.
(8) The present invention has been made to solve the above-described problem. In the communication method of the present invention, a plurality of data signal sequences are arranged on a plurality of first transmission subcarriers in a specific symbol, A sequence of data signals identical to the plurality of data signals in a plurality of second transmission subcarriers in a symbol, and the plurality of first transmission subcarriers and the plurality of second transmission subcarriers partially overlap The plurality of subcarriers so that the same data signal is arranged in each of a plurality of subcarriers in which the first transmission subcarrier and the second transmission subcarrier partially coincide with each other. A plurality of data signal sequences arranged on the first transmission subcarrier, a plurality of data signal sequences arranged on the plurality of second transmission subcarriers, or both are cyclically shifted, and then Transmitting a plurality of data signal sequences arranged on the first transmission subcarrier from the first transmission antenna, and transmitting a plurality of data signal sequences arranged on the second transmission subcarrier from the second transmission antenna; It is characterized by.
(9) The communication method of the present invention is the communication method described above, wherein the first transmission antenna and the second transmission antenna are provided in a single transmission device. .
(10) The communication method of the present invention is the communication method described above, wherein the first transmission antenna is provided in one transmission device, and the second transmission antenna is provided in another transmission device. It is characterized by being.
(11) The communication method of the present invention is the communication method described above, wherein the plurality of data signals are subjected to precoding for changing amplitude, phase, or both.
(12) The present invention has been made to solve the above-described problem, and the communication apparatus of the present invention has arranged a plurality of data signal sequences related to the same data signal sequence on the frequency axis, and arranged the same. A plurality of mapping units for outputting a data signal sequence as a transmission frequency spectrum, and controlling the plurality of mapping units based on allocation information to arrange the data signal sequences on the frequency axis so that they are the same, separated, or one An allocation information acquisition unit that performs control so as to overlap each other, and a plurality of transmission antennas that transmit transmission frequency spectra output from the plurality of mapping units at a radio frequency are provided.
(13) The present invention has been made to solve the above-described problems, and the communication device according to the present invention has a configuration in which there is no interference for one or a plurality of reception antennas and for each transmission frequency spectrum from the reception antennas. And an equalization unit that performs equalization using the MIMO weight and the MIMO weight when there is interference.
(14) The present invention has been made to solve the above-described problems, and the communication system of the present invention includes the first communication device described in (12) above and the second communication device described in (13) above. And a communication device, wherein data signals are transmitted and received between the first communication device and the second communication device.
(15) The present invention has been made to solve the above-described problems. The communication method of the present invention prepares a plurality of data signal sequences related to the same data signal sequence, and the plurality of data signal sequences. Are arranged on the frequency axis, and at that time, the plurality of sets of data signal sequences are made to be the same, separated or partially overlapped, and a plurality of sets of transmission frequency spectra arranged on the frequency axis are transmitted a plurality of times. It transmits by the radio frequency from an antenna.
(16) The present invention has been made to solve the above-described problems, and the communication method of the present invention receives a plurality of transmission frequency spectra from one or a plurality of reception antennas, and performs interference for each transmission frequency spectrum. If there is no interference, the weight in that case is used, and if there is interference, the weight in that case is used for equalization to restore the transmission frequency spectrum.
(17) The present invention has been made to solve the above-described problem, and the communication apparatus of the present invention is capable of space-time block coding, space-frequency block coding, cyclic delay diversity for a plurality of sets of data signal sequences. A transmission diversity unit that applies encoding belonging to open loop diversity, a plurality of spectral cyclic shift units that cyclically shift a plurality of data signal sequences output from the transmission diversity unit, and an output of the plurality of spectral cyclic shift units A plurality of data signal sequences arranged on the frequency axis so as to partially overlap, a plurality of mapping units that output the arranged data signal sequences as a transmission frequency spectrum, and a transmission output from the plurality of mapping units A plurality of transmit antennas that sequentially transmit the frequency spectrum at radio frequencies in two adjacent times; Characterized by including the.
(18) Moreover, the communication apparatus of the present invention is the communication apparatus described above, wherein the plurality of sets of data signal sequences output from the transmission diversity unit are a first data signal sequence and a second data signal sequence. The signal is a second signal sequence that is a conjugate complex number of the signal of the first signal sequence, a third data signal sequence different from the first data signal sequence, and a fourth data signal sequence. The signal is composed of a fourth data signal sequence obtained by multiplying a conjugate complex number of the signal of the third data signal sequence by a negative sign.
(19) The present invention has been made to solve the above-described problems, and a communication apparatus according to the present invention includes a plurality of reception antennas and an equalization unit that performs equalization for each transmission frequency spectrum from the reception antennas. An equalization unit comprising: a weight calculation unit that calculates weights used for equalization; a complex conjugate unit that selectively performs conjugate complex operations; and a negative multiplication unit that selectively performs negative multiplication. It is characterized by comprising.

According to the present invention, it is possible to perform spatial transmission with high reception quality in a communication system, a communication apparatus, and a communication method.

It is the schematic of the communication system which performs the transmission diversity of this invention. It is a schematic block diagram which shows the structure of the terminal in 1st Embodiment. It is a figure which shows an example in case the frequency allocation in each transmission antenna in the same embodiment is the same. It is a figure which shows another example in case the frequency allocation in each transmission antenna in the same embodiment leaves | separates. It is a figure which shows another example in case the frequency allocation in each transmission antenna in the embodiment overlaps only partly. It is a figure which shows an example of the transmission frame in the embodiment. It is a schematic block diagram which shows the structure of the base station in the same embodiment. It is a schematic block diagram of the equalization part in the embodiment. It is a figure which shows the other example of the frequency allocation in the same embodiment. It is a conceptual diagram which shows the example before cyclic shift in case frequency allocation with two transmission antennas overlaps partially in 2nd Embodiment. It is a conceptual diagram which shows the example after cyclic shift in case frequency allocation with two transmission antennas overlaps in 2nd Embodiment partially. It is a schematic block diagram which shows the structure of the terminal in the same embodiment. It is a schematic block diagram which shows the structure of the spectrum cyclic shift part in the embodiment. It is a flowchart explaining operation | movement of the spectrum cyclic shift part in the embodiment. It is a figure which shows the specific example before cyclic shift in case the frequency allocation by two transmission antennas overlaps partially in the same embodiment. It is a figure which shows the specific example of allocation of the overlap part in case the frequency allocation by two transmission antennas overlaps in the embodiment partially. It is a figure which shows the specific example after a cyclic shift in case the frequency allocation in two transmission antennas overlaps in the same embodiment partially. It is a figure which shows the specific example of the allocation before cyclic shift in case the frequency allocation by five transmission antennas overlaps partially in the same embodiment. It is a figure which shows the specific example of the allocation after cyclic shift in case the frequency allocation by five transmission antennas overlaps partially in the same embodiment. It is a schematic block diagram which shows the structure of the modification of the terminal in the embodiment. It is a schematic block diagram which shows the structure of the cyclic shift amount determination part in the embodiment. It is a schematic block diagram which shows the structure of the base station in the same embodiment. It is a schematic block diagram of the equalization part in the embodiment. It is a figure which shows an example of one side which makes the pair of frequency allocation in 3rd Embodiment. It is a figure before cyclic shift which shows an example of the other which makes the pair of frequency allocation in the same embodiment. It is an example of the other which makes the pair of frequency allocation in the same embodiment, and is a figure explaining allocation of the overlapping part. It is a figure after cyclic shift which shows an example of the other which makes the pair of frequency allocation in the same embodiment. It is a schematic block diagram which shows the structure of the terminal in the same embodiment. It is a schematic block diagram which shows the structure of the cyclic shift amount determination part in the embodiment. FIG. 2 is a schematic block diagram showing a configuration of a base station according to the embodiment It is a schematic block diagram which shows the structure of the equalization part in the embodiment. It is a schematic block diagram which shows the structure of the receiving antenna equalization part in the embodiment.

FIG. 1 is a schematic diagram of a communication system that performs transmission diversity.
1 includes a plurality of terminals 101-1,..., 101-n and one base station. In FIG. 1, only two terminals are shown for ease of viewing the drawing. The terminals 101-1,..., 101-n are collectively referred to as the terminal 101.
The terminal 101 includes multiple (N _t ) transmission antennas # 0 to #N _t −1, and the base station 102 includes one or multiple (N _r ) reception antennas # 0 to #N _r −. 1 is provided.

In the following description of the embodiment of the present invention, transmission by transmission diversity of data using the uplink from the terminal 101 to the base station 102 will be described. In this case, the terminal 101 may be referred to as a “transmitting device” or “first communication device”, and the base station 102 may be referred to as a “receiving device” or “second communication device”.

In the following description, transmission for transmitting the same spectrum from all transmitting antennas (this transmission is referred to as “rank number 1 transmission”) will be described, but the number of ranks lower than the number of transmitting antennas. The number of ranks may be two or more. Also, a case where one terminal 101 having a plurality of antennas performs communication using an uplink will be described. MU-MIMO (Multi-User-MIMO, multi-user mimo) in which a plurality of terminals simultaneously connect at the same frequency. In this case, known frequency allocation and signal separation processing are used in combination. In each embodiment, single carrier transmission is described as an example. However, multicarrier transmission such as OFDM or MC-CDMA may be used. Although transmission on the uplink (wireless communication line from the terminal 101 to the base station 102) will be described as an example, transmission on the downlink (wireless communication line from the base station 102 to the terminal 101) may be used.

<First Embodiment>
FIG. 2 is a schematic block diagram showing the configuration of the terminal 101 of this embodiment.
The terminal 101 includes an encoding unit 201, a modulation unit 202, a DFT unit 203, a copy unit 204, mapping units 205-0 to 205-N _t -1, reference signal multiplexing units 206-0 to 206-N _t -1, OFDM Signal generators 207-0 to 207-N _t -1, transmitters 208-0 to 208-N _t -1, transmitter antennas 209-0 to 209-N _t -1, receiver antenna 210, receiver 211, control information An extraction unit 212 and an allocation information acquisition unit 213 are provided.

In the following, a case will be described in which the same data is transmitted by single carrier transmission with the same, separated, or partially overlapping frequency allocation depending on the communication environment using the transmission antennas 209-0 to 209-N _t −1 of the terminal 101. .
Note that other known configurations of the terminal 101 are omitted in FIG. 2 for easy understanding. This also applies to the other embodiments.

A bit sequence of data such as voice data, character data, and image data is encoded into an error correction code in the encoding unit 201, and then, in the modulation unit 202, QPSK (Quadrature Phase Shift Keying), 16QAM ( Modulation such as quadrature amplitude modulation (16-value quadrature amplitude modulation) is performed and converted into modulation symbols. The output of the modulation unit 202 is input to the DFT unit 203 every N _DFT symbols, and is converted from the time domain signal to the frequency domain signal S (m) (0 ≦ m) by N _DFT point discrete Fourier transform (DFT). ≦ N _DFT −1). Hereinafter, the data signal sequence of the output signal S (m) of the DFT unit 203 may be referred to as a “first set of transmission frequency spectrums”.

The output S (m) of the DFT unit 203 is input to the copy unit 204. The copy unit 204 copies the input signal S (m) by the number of transmission antennas (N _t ), and inputs this copy to the mapping units 205-0 to 205-N _t -1.
In each mapping unit 205-0 to 205-N _t -1, transmission to predetermined N _DFT frequency points out of N _FFT point frequency points (hereinafter sometimes referred to as “subcarriers”). Frequency spectrum allocation is performed. However, N _DFT <N _FFT . The spectrum of N _FFT frequency points may be referred to as a “second set of transmission frequency spectra”.

Next, allocation in this mapping unit will be described.
In the reception unit 211, a signal transmitted from the base station 102 is received by the reception antenna 210, and the transmission signal is restored after down-conversion from the carrier frequency to the baseband signal, A / D conversion, orthogonal demodulation, and fast Fourier transform. Done. This signal is input to the control information extraction unit 212. The control information extraction unit 212 extracts control information from the received signal and inputs the control information to the allocation information acquisition unit 213.

The control information input to the allocation information acquisition unit 213 includes frequency allocation information for each of the transmission antennas 209-0 to 209-N _t -1. The allocation information acquisition unit 213 extracts the allocation information for each of the transmission antennas 209-0 to 209-N _t −1 from the control information, and assigns the allocation information to the corresponding mapping units 205-0 to 205-N _t −1. Then, the mapping units 205-0 to 205-N _t −1 are controlled. Therefore, the first set of transmission frequency spectrums is assigned to the same, separated, or partially overlapping frequency points for each of the transmission antennas 209-0 to 209-N _t -1.

An example of frequency allocation is shown in FIGS. 3A to 3C. The frequency allocation for each of the transmission antennas 209-0 to 209-N _t −1 in the present embodiment depends on the propagation path state (communication environment) between the terminal 101 and the base station 102, as shown in FIG. 3A to FIG. 3C. There are three main patterns.

FIG. 3A shows the case where there are two transmission antennas of the terminal 101 (N _t = 2), and the codes of the transmission antennas in this case are shown as # 0 and # 1 for easy understanding.
) Shows a case where the same frequency allocation is performed in each of the transmission antennas # 0 and # 1. That is, the first set of transmission frequency spectrums S (0) to S (5) is continuously assigned to the frequency points of indexes 4 to 9 by the transmission antennas # 0 and # 1. In addition, the index of a frequency point may be called a frequency index. FIG. 3B shows a case where frequency allocation is performed by using separate transmission antennas # 0 and # 1. That is, the first set of transmission frequency spectrums S (0) to S (5) are continuously assigned to the frequency points of indexes 1 to 6 by transmission antenna # 0, and the transmission frequency spectrum S (0). In this case, S (5) is continuously assigned to the frequency indexes 8 to 13 with respect to the transmission antenna # 1.

FIG. 3C shows a case where the frequency assignments at the transmission antennas # 0 and # 1 partially overlap. That is, transmission frequency spectrums S (0) to S (5) are continuously assigned to frequency indexes 1 to 6 for transmission antenna # 0, and transmission frequency spectrums S (0) to S (5) However, the frequency index 5 to 10 is continuously allocated to the transmission antenna # 1, and as a result, the frequency allocation is the same for the frequency indexes 5 and 6. In FIGS. 3A to 3C, the second set of transmission frequency spectrums after allocation is configured by the whole spectrum of frequency indexes 0 to 14.

3A to 3C show an example in which the first set of transmission frequency spectra is continuously assigned to a plurality of frequency points, but may be assigned discretely.

As described above, in this embodiment, the first set of transmission frequency spectra can be freely arranged at a plurality of frequency points in each of the transmission antennas 209-0 to 209-N _t −1. Allows flexible frequency allocation. Note that the mapping unit assigns zero to the frequency points to which no spectrum is assigned.

N _FFT point outputs of the mapping units 205-0 to 205-N _t −1 are respectively input to reference signal multiplexing units 206-0 to 206-N _t −1.
In the reference signal multiplexing units 206-0 to 206-N _t -1, the base station 102 uses a sounding reference signal SRS (Sounding Reference Signal) used for determining a frequency point used by the terminal 101 for communication, Then, the demodulation reference signal DMRS (DeModulation Reference Signal) used for compensating the propagation path of the received signal is multiplexed, and the transmission frame is finally constructed.

FIG. 4 shows an example of a transmission frame in each path with the transmission antennas 209-0 to 209-N _t −1. This transmission frame is common to the transmission antennas 209-0 to 209-N _t -1.
The vertical axis represents the index of the SC-FDMA symbol on the time axis, and the horizontal axis may be referred to as a frequency point on the frequency axis (sometimes referred to as “subcarrier”. This means the same as “resource element”. Is).
One frame is composed of a total of 14 SC-FDMA symbols from the 0th to the 13th, and the third and tenth SC-FDMA symbols (shown by solid squares) have the same frequency as the data signal. With the allocation, a demodulation reference signal DMRS is transmitted. In the last thirteenth SC-FDMA symbol (indicated by a shaded square), a data signal or a sounding reference signal SRS is transmitted. Which is sent is notified from the base station 102.
Unlike DMRS, SRS is not always transmitted using the same frequency as a data signal. That is, the DMRS is a reference signal transmitted by the terminal 101 so that the base station 102 can grasp the detailed propagation path state in the band in which the data spectrum is transmitted, whereas the SRS is a rough signal in the system band. This is a reference signal transmitted by the terminal 101 so that the base station 102 can grasp the propagation path quality.

Transmission frame generated by the reference signal multiplexing units 206-0 ~ _206-N t -1 is input to the OFDM signal generating unit 207-0 ~ _207-N t -1.

The OFDM signal generators 207-0 to 207-N _t −1 apply an inverse fast Fourier transform IFFT (Inverse Fast Fourier Transform) of N _FFT points and perform conversion from a frequency domain signal to a time domain signal. A cyclic prefix CP (Cyclic Prefix) corresponding to the guard time is inserted into the converted SC-FDMA symbol. The SC-FDMA symbol after CP insertion is then output to transmitting sections 208-0 to 208-N _t -1.
In the transmission units 207-0 to 207-N _t -1, this symbol is followed by D / A (digital-analog) conversion, quadrature modulation, analog filtering, up-conversion from baseband to carrier frequency, etc. Then, the radio frequency signal carrying the SC-FDMA symbol after CP insertion is transmitted from the transmission antennas 209-0 to 209-N _t −1 to the base station 102.

As described above, the signal transmitted from the terminal 101 is received by the N _r reception antennas of the base station 102 via the radio propagation path.

The signal processing in the base station 102 will be described with reference to FIG.
FIG. 5 is a schematic block diagram showing the configuration of the base station 102 of the present embodiment.
Base station 102 may receive antennas _{501-0 ~ 501-N r -1,} OFDM signal receiving unit 502-0 ~ _502-N r -1, the reference signal separating unit 503-0 ~ _503-N r -1, demapping Sections 504-0 to 504-N _r -1, an equalization section 505, an IDFT section 506, a demodulation section 507, a decoding section 508, a propagation path estimation section 509, a scheduling section 510, a transmission section 511, and a transmission antenna 512.

Hereinafter, a case will be described in which a signal transmitted from the terminal 101 by single carrier transmission is received using each of the receiving antennas 501-0 to 501-N _r −1 of the base station 102.
Note that other known configurations included in the base station 102 are omitted in FIG. 5 for easy understanding. This also applies to the other embodiments.

Signals received by the N _r receiving antennas 501-0 to 501-N _r −1 of the base station are input to OFDM signal receiving sections 502-0 to 502-N _r −1, respectively. Each OFDM signal receiving unit 502-0 ~ _502-N r -1, down conversion, analog filtering from the carrier frequency to a baseband signal, A / D (analog - digital) conversion, cyclic every SC-FDMA symbol After the prefix CP is removed, N _FFT point fast Fourier transform (FFT) is applied to convert the time domain signal to the frequency domain signal, and the spectrum of the N _FFT point is converted to the reference signal separation unit 503-0˜ 503-N _r −1 respectively.

Reference signal demultiplexing sections 503-0 to 503-N _r −1 demultiplex a reference signal such as a demodulation reference signal DMRS and a sounding reference signal SRS and a data signal, and the reference signal is input to a propagation path estimation section 509, where the data signal Are respectively input to the demapping units 504-0 to 504-N _r -1.
The propagation path estimation unit 509 uses the input demodulation reference signal DMRS to transmit a wireless propagation path (wireless propagation) between each transmission antenna of the terminal 101 and the reception antenna of the base station 102 in the band in which the data signal is transmitted. Estimate the phase and amplitude of the propagation constant of the road. The obtained propagation path estimation value is input to the equalization unit 505.

Further, the propagation path estimation unit 509 uses the received sounding reference signal SRS to transmit the transmission antennas 209-0 to 209-N _t −1 of the terminal 101 and the base station in the entire system band as well as the band in which the data signal is transmitted. The channel quality of the receiving antennas 501-0 to 501 -N _r −1 of the station 102 is estimated (channel quality estimation using only the SRS amplitude value or power value). The channel quality estimation value in the entire system band estimated by the channel estimation unit 509 is input to the scheduling unit 510.
Scheduling section 510 determines frequency allocation for each of transmission antennas 209-0 to 209-N _t −1 of terminal 101 based on the input channel quality estimation value. In frequency allocation, frequency points (subcarriers) having high propagation path quality are independently selected by the transmission antennas 209-0 to 209-N _t −1 of the terminal 101. Note that frequency allocation may be performed in consideration of not only channel quality but also correlation between antennas, frequency allocation of other mobile stations, and the like.

For example, FIG. 3A, FIG. 3B, and FIG. 3C described above are examples in which 6 points are selected from the frequency points with the highest gain in each of the transmission antennas # 0 and # 1. Since the propagation path gain is different for each transmission antenna and frequency points are selected independently, frequencies separated by each antenna may be assigned as shown in FIG. 3B, or only partially overlap as shown in FIG. 3C. And the frequency allocation at each transmitting antenna may be the same as shown in FIG. 3A.

The data signals separated by the reference signal separation units 503-0 to 503-N _r -1 in FIG. 5 are input to the demapping units 504-0 to 504-N _r −1, respectively. In each of the demapping units 504-0 to 504-N _r -1, the data at the frequency point used for transmission is transmitted with respect to the first set of transmission frequency spectrum S (m) from the received reception spectrum of N _FFT points. The reception spectrum of the signal is extracted.

For example, let us consider extracting the transmission frequency spectrum S (1) in the frequency allocation as shown in FIG. 3B. Transmission of S (1) is performed using the second frequency point (frequency index is 2) from the transmission antenna # 0 of the terminal 101 and the ninth frequency point (frequency index is 9) from the transmission antenna # 1. Is called. Therefore, each demapping unit 504-0 to 504-N _r -1 (in this example, demapping units 504-0 and 504-1) extracts the data signals of the second and ninth frequency points, and These data signals are input to the equalization unit 505.
Although only the transmission frequency spectrum S (1) has been described above, the same processing is performed for other transmission frequency spectra. That is, if the number of transmission frequency spectrums of the first set is N _DFT , the number of transmission antennas of the terminal 101 is N _t , and different frequency allocation is performed for all antennas, N _DFT × N _t values Is input to the equalization unit. Note that the value to be input differs depending on the number of allocation patterns. When the same frequency allocation is performed for all transmission antennas (in the case of FIG. 3A), _NDFT × 1 value is input to the equalization unit 505. It will be.

The same applies to the case of partially overlapping allocation as shown in FIG. 3C. When the transmission frequency spectrum S (1) is extracted, the data signals of the second and sixth frequency points are extracted and input to the equalization unit 505. To do. However, the second frequency point can receive the transmission frequency spectrum S (1) without interference unless another terminal transmits the data signal using the second frequency point. However, at the sixth frequency point, the transmission antenna # 0 The transmission frequency spectrum S (5) transmitted from the terminal becomes interference. For this reason, in the equalization part 505, the process which suppresses the interference with respect to transmission frequency spectrum S (1) by transmission frequency spectrum S (5) is performed. This point will be described in detail below.

FIG. 6 is a block diagram showing details of the equalization unit 505.
The equalization unit 505 includes a combining unit 601, a weight multiplication unit 602, a channel matrix generation unit 603, a SIMO weight calculation unit 604, and a MIMO weight calculation unit 605.
N _DFT × N _t values are input to the equalization unit 505 from the demapping unit 504-0. Similarly, N _DFT × N _t values are also input from the last demapping unit 504 -N _r −1. Accordingly, a total of N _DFT × N _t × N _r values are input to the equalization unit 505 from the demapping units 504-0 to 504 -N _r −1.

Next, processing performed by the equalization unit 505 of the base station 102 in the case of frequency allocation in FIG. 3C (in the case of partial overlap) will be described.
The equalization unit 505 performs equalization independently for each transmission frequency spectrum S (m).

As an example, an example in which the transmission frequency spectrum S (1) is equalized will be described.
When the k-th frequency point of the n receiving antenna of the _{N r} the base station 102 is the receive antenna (frequency index k) to the received signal at the _R n _{(k), R} n and (2) _R n ( 6) is expressed by the following formula 1, respectively.

Here, H _{n, l} (k) is a channel gain at the k-th frequency point between the l-th transmitting antenna of the terminal 101 and the n-th receiving antenna of the base station 102, and Equation 1 is noise at the receiver. And the expression that ignores interference from other cells.
Since the transmission frequency spectrum S (1) is received at two frequency points, that is, the second frequency point and the sixth frequency point, it can be considered that the transmission frequency spectrum S (1) is received by twice the number of reception antennas.
Therefore, the combining unit 601 in the equalizing unit 505 combines the spectrum for each reception frequency point to generate a vector R _{S (1)} of N _r N _t × 1 (N _r N _t rows and 1 column). In this example, the vector R _{S (1)} input by the combining unit 601 to the weight multiplication unit 602 is expressed by the following Equation 2.

Further, in the above equation, at the second frequency point of the transmission antenna # 0 of the terminal 101, it can be modified as follows by considering that the propagation path gain of the interference signal S (5) is zero.

In the propagation path matrix generation unit 603 in FIG. 6, information necessary for the propagation path estimation value input from the propagation path estimation unit 509 to form the matrix of H _{S (1) in} Expression 3 is input from the combining unit 601. Is done.
The propagation path matrix generation unit 603 inputs the estimated value of H _{S (1)} to the MIMO weight calculation unit 605 when the obtained estimated propagation path matrix is a matrix, that is, when there is interference. On the other hand, when the estimated channel matrix obtained is actually a vector or a scalar, that is, when there is no interference, the estimated value of H _{S (1)} is input to the SIMO weight calculation unit 604.
Since H _{S (1)} in Equation 3 is a 2N _r × 2 matrix (2N _r rows and 2 columns matrix), the estimated value of H _{S (1)} is input to the MIMO weight calculation unit 605.

The MIMO weight calculation unit 605 calculates a MIMO weight vector w _{S (1)} by which the received spectrum vector of Equation 3 is multiplied in order to equalize the transmission frequency spectrum S (1). The weight vector w _{S (1)} is expressed by the following Equation 4.

This means that the right side of Equation 4 is calculated, and a 1 × 2N _r row vector w _{S (1)} necessary for equalization of _{S (1)} is extracted. Here, σ ² is an average noise power, I is a 2 × 1 unit matrix in Equation 3 because the signal vector is a 2 × 1 vector, and equalization of S (5) is performed using the weight w _1. However, it is not used for equalization of S (1). T represents a matrix (vector) transposition process, H represents a Hermite transposition process, and -1 represents an inverse matrix operation process.

That is, MIMO weight calculation section 605 uses the estimated value of propagation path matrix H _{S (1)} input from propagation path matrix generation section 603 and the average noise power estimation value input from a noise estimation section (not shown ₎ , Calculation of Equation 4 with inverse matrix calculation is performed to calculate a weight vector w _{S (1)} and input to the weight multiplier 602.
As an example, the noise estimation is obtained by subtracting a signal obtained by multiplying a propagation path estimation value at each frequency obtained by the DMRS and a DMRS in the frequency domain from a reception signal of the demodulation reference signal DMRS in the frequency domain. Therefore, the square of the absolute value of the subtraction result is obtained at each frequency and then averaged.

Note that Equation 4 uses MMSE (MinimumMiniMean Square Error) weights as an example, but what kind of weights such as ZF (Zero Forcing) weights and MRC (MaximumRatio Combining) weights that do not consider the average noise power? Reference weights can also be used. Furthermore, other signal separation methods such as iterative equalization processing and MLD (Maximum Likelihood Detection) can be used.

In this way, when there is interference at any frequency point at a plurality of frequency points at which the same spectrum is transmitted (S (1) is transmitted at the second and sixth frequency points in the above example). Can generate a MIMO diversity weight in consideration of interference (S (5) becomes interference at the sixth frequency point in the above example), thereby effectively obtaining transmission diversity gain.

The weight multiplication unit 602 multiplies _{RS (1)} input from the combining unit 601 and w _{S (1)} input from the MIMO weight calculation unit 604 or the SIMO weight calculation unit 605, and performs equalization. Output

Is calculated. The output after this equalization is expressed by the following equation.

In the above, the equalization process of the transmission frequency spectrum S (1) in the equalization unit 505 has been described.

Next, as in the transmission frequency spectrum S (3) of FIG. 3C, a description will be given of a spectrum equalization process in which interference by other antennas of the terminal 101 does not occur at the transmitted frequency point.
Reception signals R _n (4) and R _n (8) at the n-th receiving antenna of the base station 102 at the fourth and eighth frequency points at which the transmission frequency spectrum S (3) is transmitted from the terminal 101 are respectively This is expressed by Equation 7.

Here, H _{n, l} (k) is a channel gain at the k-th frequency point between the l-th transmission antenna of terminal 101 and the n-th reception antenna of base station 102. Expression 7 is an expression that ignores noise.
Since the transmission frequency spectrum S (3) is received at the fourth frequency point and the eighth frequency point, it can be considered that the transmission frequency spectrum S (3) was received with twice the number of reception antennas. Therefore, the combining unit 601 in the equalizing unit 505 combines the spectrum for each reception frequency point to generate a vector R _{S (3)} of N _r N _t × 1.
In this example, the vector R _{S (3)} input by the combining unit 601 to the weight multiplication unit 602 is expressed by the following equation.

Furthermore, the above equation can be modified as follows.

The propagation path matrix generation unit 603 receives, from the combining unit 601, information for configuring a matrix (actually a vector) of the H _{S (3)} of Equation 9 in which the propagation path estimation value input from the propagation path estimation unit 509 is Entered. The propagation path matrix generation unit 603 generates an estimation matrix of H _{S (3)} in Equation 9 using the input propagation path estimation value. Here, since H _{S (3)} is a 2N _r × 1 vector in Equation 9, the estimated value of H _{S (3)} is input to the SIMO weight calculation unit 604.
In order to equalize the transmission frequency spectrum S (3), the SIMO weight calculation unit 604 calculates a SIMO weight vector w _{S (3)} by which the reception spectrum of the nth reception antenna at the kth frequency point is multiplied. The weight vector w _{S (3)} is generally represented by the following Expression 10.

Here, σ ² is the average noise power.

That is, the weight calculation unit 602 uses the estimated value of the propagation path matrix HS ₍₃₎ input from the propagation path matrix generation unit 603 and the average noise power estimation value input from the noise estimation unit (not shown ₎ , and performs inverse processing. A weight vector w _{S (3)} is calculated based on Equation 10 that does not involve matrix operation, and is input to the weight multiplier 602. Note that the weight vector is not limited to the MMSE weight as described above for the case of the transmission frequency spectrum S (1).

Thus, when there is no interference at any frequency point at a plurality of frequency points at which the same spectrum is transmitted (in the above example, S (3) is transmitted at the fourth and eighth frequency points). By generating a weight that does not involve an inverse matrix operation, a transmission diversity gain can be obtained efficiently.

As described above, in the equalization unit 505 of the present embodiment, when there is a transmission signal that causes interference, the weight is calculated using the MIMO weight calculation unit 605 with inverse matrix calculation, and when there is no transmission signal that causes interference. By calculating the weight using the SIMO weight calculation unit 604 that does not involve an inverse matrix operation, it is possible to perform appropriate signal separation while suppressing an increase in the amount of calculation.
The weight multiplier 602 multiplies the vector R _{S (3)} input from the combiner 601 by the weight vector w _{S (3),} and the transmission frequency spectrum after equalization is as follows:

Is calculated. The equalized transmission frequency spectrum is expressed by the following equation.

Heretofore, the equalization processing of S (1) and S (3) in the equalization unit 505 has been described.
The equalization unit 505 performs equalization processing on all transmission frequency spectra S (m) (0 ≦ m ≦ N _DFT −1), and inputs the equalized spectrum to the IDFT unit 506.

In the above description, the equalization process of S (3), which is a spectrum without interference from other antennas in FIG. 3C, has been described. However, in the case of frequency allocation as in FIG. 3B, there is no transmission signal that causes interference. Then, equalization processing using the SIMO weight calculation unit 604 is performed on all frequency spectra as in the transmission frequency spectrum S (3).

In the above, the case where transmission is performed from the two transmission antennas of the terminal 101 has been described. Next, the case where the number of antennas is three or more will be described.

FIG. 7 shows an example of frequency allocation when the number of transmission antennas of the terminal 101 is five. That is, transmission frequency spectrums S (0) to S (5) are continuously assigned to frequency index 8 to 13 for transmission antenna # 0, and to frequency index 3 to 8 for transmission antenna # 1. Assigned continuously to frequency index 1-6 for transmit antenna # 2, assigned continuously to frequency index 6-11 for transmit antenna # 3, and transmit antenna # 4. In contrast, the frequency indexes 15 to 20 are continuously assigned.
The equalization unit 505 performs equalization processing on all spectra S (m) (0 ≦ m ≦ N _DFT −1). Hereinafter, the transmission frequency spectrum S (0) will be described as an example.
When the received signal at the k-th frequency point of the n-th reception of the base station 102 is R _n (k), the first, third, sixth, eighth, and fifteenth when the transmission frequency spectrum S (0) is transmitted. The received signal at the frequency point is expressed by the following Equation 13, respectively.

Here, H _{n, l} (k) is a channel gain at the k-th frequency point (frequency point-intex is k) between the l-th transmitting antenna and the n-th receiving antenna, and Equation 13 is an equation that ignores noise. It has become. Since S (0) is received at five frequency points, it can be considered that it has been received with five times the number of receiving antennas. Therefore, the combining unit 601 in the equalizing unit 505 in FIG. 6 combines the spectrum for each reception frequency to generate a vector R _{S (0)} of N _r N _t × 1. A vector R _{S (0)} input by the combining unit to the weight multiplication unit is expressed by the following Equation 14.

In Equation 14, since H _{S (0)} is a 5N _r × 4 matrix, the propagation path matrix generation unit 603 inputs the estimated value of H _{S (0)} to the MIMO weight calculation unit 605, and the above Equation 4 The MMSE weight is generated in the same manner as the above.
However, since the signal vector in Equation 14 is a 4 × 1 (4 rows and 1 column) vector, I in Equation 4 is a 4 × 4 unit matrix. That is, the MIMO weight calculation unit 605 performs the following processing.
(1) Extract all the frequencies at which the target spectrum was received, (2) combine the received signals of each frequency, generate a received signal sequence vector, and (3) configure with the spectrum included in any frequency (4) Calculate a propagation path matrix such that “received signal string vector = propagation path matrix × transmission signal string vector”, and (5) depending on whether the propagation path matrix is a matrix or not. That is, the MIMO weight calculation unit 605 or the SIMO weight calculation unit 604 is selected depending on whether there is interference from another antenna.

By performing such processing, equalization processing can be performed even when the terminal 101 has three or more transmission antennas.

In addition, in order to avoid an increase in the amount of calculation due to performing a large inverse matrix operation on all transmission frequency spectra, a configuration may be adopted in which separation is performed after each frequency and then synthesis is performed.
For example, in the case of Expression 14, if attention is paid only to the first and fifteenth frequency points, equalization can be performed by the SIMO weight calculation 604 without performing an inverse matrix operation, and then attention is paid to the third and eighth frequency points. Then, equalization is performed by performing a 3 × 3 inverse matrix operation, and finally, focusing on the sixth frequency point, equalization is performed by performing a 3 × 3 inverse matrix operation, and three outputs are combined into an MMSE By doing so, 4 × 4 inverse matrix operation can be avoided. In the case of Equation 14, when equalization can be performed accurately only with the first and fifteenth frequency points, the third, sixth, and eighth frequency points may not be used for the equalization processing in order to reduce the amount of calculation. is there.

The output of the weight multiplication unit 602 is input as the output of the equalization unit 505 to the IDFT unit 506 in FIG. The IDFT unit 506 performs IDFT (Inverse Discrete Fourier Transform) of N _DFT points on the input equalized transmission frequency spectrum S (m) (0 ≦ m ≦ N _DFT −1) to obtain a frequency domain signal. Convert to time domain signal. The output of the IDFT unit 506 is input to the demodulation unit 507, and conversion from the symbol format to the bit format is performed based on the modulation scheme performed by the terminal 101.
The signal converted into bits is input to the decoding unit 508, subjected to error correction decoding, and then output to the outside as bit series data.

As described above, in this embodiment, when the terminal 101 having a plurality of transmission antennas transmits the same data signal from each transmission antenna, it is limited to performing transmission using the same frequency point (subcarrier). In addition, transmission can be performed even if different frequency points are used for each antenna. As a result, transmission can be performed using a frequency point with a high propagation path gain at each transmission antenna of the terminal 101, so that received power at the base station 102 can be improved. In addition, since signals transmitted from the respective transmission antennas of terminal 101 are received at a plurality of frequency points in base station 102, good transmission characteristics are obtained by frequency synthesis in equalization section 505 of base station 102. It is done.

In the present embodiment, as shown in FIGS. 3A to 3C and FIG. 7, the first set of transmission frequency spectrums are continuously assigned to form the second set of transmission frequency spectra. The present invention can also be applied to the case where the first set of transmission frequency spectrums are allocated discretely. Further, in this embodiment, since single carrier transmission is used, weights are generated in consideration of the fact that spectra transmitted at different frequencies are combined in the equalization unit, as in Expression 4 and Expression 11. However, other transmission schemes such as OFDM may be used instead of single carrier transmission. For example, in the case of OFDM, each frequency (subcarrier) is not connected in a DFT relationship. Weights that do not take propagation path conditions into account can be used.

<Second Embodiment>
In the first embodiment, since different transmission frequency spectra are transmitted at the same frequency point, it is necessary to perform signal separation using spatial filtering that multiplies MMSE weights or the like or MLD (Maximum Likelihood Detection). It was.
However, in order to perform spatial filtering, since it is desirable that the base station (receiver) has a number of reception antennas equal to or greater than (number of interference signals + 1), there is a problem that the size of the base station increases.
Further, although interference can be greatly reduced by performing MLD and iterative processing in the base station, there arises a problem that the circuit scale and signal processing delay increase. Furthermore, it is extremely difficult to completely remove interference by any signal separation method, and the characteristics are always degraded by residual interference.

Therefore, as a second embodiment, transmission diversity that performs transmission processing so that interference does not occur in the base station will be described.
In the following description, the terminal of the present embodiment is denoted by reference numeral 101a, and the base station is denoted by reference numeral 102a.

8A, 8B is the number of transmitting antennas N _t of the terminal 101a and 2, the frequency points to be used for transmitting the respective transmit antennas shows a conceptual diagram of an example that partially overlap.
As shown in FIG. 8A, when spectrums are allocated to data signals in order from the low frequency to the high frequency with respect to the allocation of each transmission antenna, a plurality of transmission frequency spectrums I transmitted from the 0th transmission antenna (transmission antenna # 0). And the front of a plurality of transmission frequency spectrums II transmitted from the first transmission antenna (transmission antenna # 1) are transmitted at the same frequency point, resulting in interference. Therefore, as shown in FIG. 8B, the first transmission antenna cyclically shifts the transmission frequency spectrum within the allocated frequency point. As a result of applying the cyclic shift, the transmission frequency spectrum II ′ is obtained, and the same frequency spectrum is obtained at the frequency point where the allocation is overlapped between the 0th transmission antenna and the first transmission antenna. Then, transmission frequency spectra I and II ′ are transmitted from the 0th transmission antenna and the first transmission antenna, respectively.

As described above, in the present embodiment, the transmission frequency spectrum is transmitted with a cyclic shift within the allocated frequency point so that interference does not occur at the receiving antenna.

FIG. 9 is a schematic block diagram showing the configuration of the terminal 101a of this embodiment.
Terminal 101a includes an encoding unit 901, modulation section 902, DFT section 903, precoding section 904, spectrum cyclic shift section 905-0 ~ 905N _t -1, the mapping unit 906-0 ~ _906-N t -1, the reference signal Multiplexers 907-0 to 907-N _t -1, OFDM signal generators 908-0 to 908-N _t -1, transmitters 909-0 to 909-N _t -1, transmit antennas 910-0 to 910-N _t- 1, receiving antenna 911, receiving unit 912, control information extracting unit 913, allocation information acquiring unit 914, PMI acquiring unit 915, and cyclic shift amount determining unit 916.

Hereinafter, a case will be described in which the same data is transmitted by single carrier transmission with different frequency assignments using each of the transmission antennas 910-0 to 910-N _t −1 of the terminal 101a.

A bit sequence of data such as voice data, character data, and image data is encoded by an encoding unit 901 into an error correction code, and then modulated by a modulation unit 902 such as QPSK or 16QAM to be converted into a modulation symbol. Is converted. The output of the modulation unit 902 is input to the DFT unit 903 every N _DFT symbols, and is converted from a time domain signal to a frequency spectrum by N _DFT point discrete Fourier transform.

The output S (m) (0 ≦ m ≦ N _DFT −1) of the _DFT unit 903 is input to the precoding unit 904.
In the first embodiment, the output of the DFT unit 203 (FIG. 2) is input to the copy unit 204 (FIG. 2). However, in this embodiment, the output is input to the precoding unit 904. As shown in FIG. 8B, when the same transmission frequency spectrum is transmitted at the same frequency point by the 0th transmission antenna (transmission antenna # 0) and the first transmission antenna (transmission antenna # 1), This is because the signals from the transmitting antennas of the terminal 101a may be received by canceling each other at the base station 102a. Therefore, in this embodiment, precoding is performed on the first set of frequency spectrum signals, which are output signals of DFT 903, so that signals from each transmission antenna are in-phase combined at the reception antenna, and after precoding is performed. Are output to spectrum cyclic shift sections 905-0 to 905-N _t -1.
Therefore, in this embodiment, the case where the terminal 101a includes the precoding unit 904 instead of the copy unit will be described.

In the precoding unit 904, precoding is performed based on the information of the precoding matrix acquired by the PMI acquisition unit 915.
Here, the PMI acquisition unit 915 extracts a precoding matrix indicator PMI (Precoding Matrix Indicator) from the control information input from the control information extraction unit 913 and inputs it to the precoding unit 904. The PMI is determined according to the propagation path between the transmission antenna and the reception antenna in the base station 102a, and is usually received SINR (Signal to Interference plus Noise power Ratio), reception SNR. (Signal to Noise power Ratio) or PMI that maximizes the channel capacity is selected, and this PMI is notified to the terminal 101a.

The precoding unit 904 multiplies the first set of transmission frequency spectra S (m) input from the DFT unit 903 by the precoding matrix w (m). Here, the precoding matrix w (m) with the rank number R is an N _t × R matrix. In this embodiment, since the rank number R is 1, the precoding matrix w (m) is an N _t × 1 vector.
A vector S (m) (0 ≦ m ≦ N _DFT −1) output from the precoding unit 904 is expressed by the following equation.

In Equation 15, the precoding matrix w (m) depends on the frequency index m, but the same precoding matrix w may be used for all frequency indexes in order to reduce the amount of notification information from the base station 102a. it can.

In order to suppress the amount of notification information, the PMI is used as an index of a quantized precoding matrix (described in the codebook (code table)) instead of the precoding matrix itself, and the base station 102a sends the index to the terminal 101a. You may make it notify PMI.
The precoding matrix (2 × 1 matrix, that is, precoding vector) w of rank 1 (also referred to as 1 layer number and 1 stream number) in two transmit antennas is composed of the six vectors shown in Table 1 in 3GPP. The The base station 102a selects one of the codebook indexes and notifies the terminal 101a as PMI.

Further, when the same precoding matrix is used in all spectrum indexes, precoding is performed in the frequency domain in the configuration of the terminal 101a in FIG. 9, but precoding may be performed in the time domain.
In the following description, it is assumed that the same precoding is performed for all spectrum indexes, and that precoding is performed using the N _t × 1 precoding vector w.

In the present embodiment, a frequency division bidirectional communication FDD (Frequency Division Duplex) system is assumed, and the precoding vector used for transmission in the terminal 101a is reported from the base station 102a. However, in a time division bidirectional communication TDD (Time Division Division Duplex) system using the same frequency band in the uplink and the downlink, the terminal 101a may determine a precoding vector in the uplink using a downlink reference signal. Therefore, it is possible not to notify the precoding vector (or codebook index). Further, instead of performing precoding according to the propagation path, it is also possible to perform precoding with a pattern determined in advance by transmission and reception.

The signal S _n (m) at the n-th transmission antenna output from the precoding unit 904 in FIG. 9 is input to the spectrum cyclic shift unit 905-n. That is, the signal S ₀ (m) for the 0th transmission antenna 910-0 is input to the spectrum cyclic shift section 905-0, and so on, at the last N _t −1 transmission antenna 910-N _t −1. The signal S _Nt−1 (m) is input to the spectrum cyclic shift unit 905 -N _t −1.

FIG. 10 is a block diagram showing a specific configuration of spectrum cyclic shift section 905. Note that the configurations of the N _t spectral cyclic shift units 905-0 to 905-N _t -1 are the same, and the common configuration is denoted by reference numeral 905.
The spectrum cyclic shift unit 905 includes a shift unit 1001, a modulo operation unit 1002, and an index change unit 1003.
Cyclic shift amount delta _n inputted from cyclic shift amount determining unit 916 is input to the shift unit 1001. The cyclic shift amount determination unit 916 will be described later.

The shift unit 1001 adds the cyclic shift amount Δ _n input under the control of the cyclic shift amount determination unit 916 to the N _DFT number sequences from 0 to N _DFT −1, and sends the result to the modulo arithmetic unit 1002 input. For example, when N _DFT = 6 and Δ _n = 4, a sequence 4, 5, 6, 7, 8, 9 obtained by adding 4 to the sequences 0, 1, 2, 3, 4, 5 is used as the modulo arithmetic unit 1002. Entered. The modulo operation unit 1002 performs _{N DFT} = 6 _(calculated remainder when divided by _{N DFT)} modulo operation with respect to the sequence input from the shift unit 1001, and inputs the index change portion 1003. For example, in the above example, since N _DFT = 6, the output of the modulo arithmetic unit 1002 is the sequence 4, 5, 0, 1, 2, 3.
In the index changing unit 1003, the frequency indexes 0, 1, 2, 3, 4, 5 of the transmission frequency spectrum after precoding input from the precoding unit 904 are converted into the sequence of numbers 4, 5, 0 input from the modulo arithmetic unit 1002. , 1, 2 and 3 are changed.

In the above example, the index changing unit 1003 of the spectrum cyclic shift unit 905-n transmits the pre-coded transmission frequency spectrums S _n (0), S _n (1), S _n (2), S _n (3), S _n (4), S _n (5) and “4, 5, 0, 1, 2, 3” are input as frequency indexes from the modulo operation unit. In the index changing unit, the transmission frequency spectrums S _n (4), S _n (5), S _n (0), S _n (1), S _n (2), and S _n (3) are rearranged according to the frequency index. _Are output as S ′ _n (0), S ′ _n (1), S ′ _n (2), S ′ _n (3), S ′ _n (4), and S ′ _n (5). Become.

FIG. 11 is a flowchart for explaining the operation of the spectrum cyclic shift section 905-n.
First, a temporary sequence 0, 1, 2,. . . , N _DFT −1. (Step S1101). Then, the value of this sequence increases by the amount of cyclic shift delta _n input from the cyclic shift amount determining unit 916 (step S1102). A modulo operation is performed with the numerical value N _DFT on the increased numerical sequence (step S1103). Next, the frequency index of the first set of transmission frequency spectrums after the precoding input from the above-described precoding unit 904 is changed using the sequence subjected to this modulo operation (step S1104). Subsequently, the obtained transmission frequency spectrum is output to mapping section 906.
In this way, spectrum cyclic shift section 905 performs cyclic shift on transmission frequency spectrum S _n (m) output from precoding section 904 by cyclic shift amount Δ _n input from cyclic shift amount determination section 914. .
When the transmission frequency spectrum input from the precoding unit 904 to the spectrum cyclic shift unit is S _n (m) and the cyclic shift amount is Δ _n , the output S ^′ _n (m) of the spectrum cyclic shift unit 905 is given by Given in.

The spectrum S ′ _n (m) output from the spectrum cyclic shift unit 905-n is input to the mapping unit 906-n in FIG. However, 0 ≦ n ≦ N _t −1.
Since the signal processing from the mapping units 906-0 to 906-N _t −1 to the antennas 910-0 to 910-N _t −1 is the same as that in the first embodiment, the description thereof will be used. However, the demodulation reference signal DMRS is transmitted after being multiplied by the same precoding vector w as the data signal.

Here, the signal processing in the spectrum cyclic shift sections 905-0 to 905-N _t −1 in FIG. 9 will be described.

12A to 12C, the number of transmission antennas N _t is 2, the number of DFT points N _DFT is 6, and the 0th transmission antenna (transmission antenna # 0) and the first transmission antenna (transmission antenna # 1) are used for transmission. An example where frequency points partially overlap is shown.
That is, in FIG. 12A, the first set of transmission frequency spectrums S ₀ (0) to S ₀ (5) is assigned to the frequency points of indexes 1 to 6 for the _0th transmission antenna, and One set of transmission frequency spectrums S ₁ (0) to S ₁ (5) is assigned to frequency points of indexes 5 to 10.
When a spectrum of frequency spectrum S (m) (0 ≦ m ≦ 5) composed of six spectra is assigned in order from a low frequency point to a high frequency point for each antenna assignment as shown in FIG. 12A, For example, the frequency spectrum S ₀ (4) is transmitted from the 0th transmission antenna at the fifth frequency point, and the transmission frequency spectrum S ₁ (0) is transmitted from the first transmission antenna. At the sixth frequency point, the frequency spectrum S ₀ (5) is transmitted from the 0th transmission antenna, and the frequency spectrum S ₁ (1) is transmitted from the first transmission antenna.

In this way, when the frequency points to be used are different for each antenna, different spectrums are transmitted from the respective transmission antennas at the frequency points at which the allocation is partially overlapped. Therefore, inter-antenna interference occurs at the base station.
Therefore, in the present embodiment, the same transmission frequency spectrum is transmitted from the 0th transmission antenna and the first transmission antenna at overlapping frequency points. That is, as shown in FIG. 12B, at the fifth and sixth frequency points of the first transmission antenna, the transmission frequency spectrums S ₁ (4) and S ₁ (5) are transmitted, respectively, similarly to the transmission frequency spectrum of the zeroth transmission antenna. To do.

Here, although the sub-indexes (subscripts in the transmission frequency spectrum such as S ₀ (4) and S ₁ (4)) of the transmission frequency spectrum transmitted from each transmission antenna are different, they are expressed by Equation 15. Thus, the transmission frequency spectrums S ₀ (4) and S ₁ (4) are only different in phase because they are multiplied by the precoding vector w, and are originally the same spectrum S (4). . Further, the precoding vector w is determined not to cause interference because the spectrum transmitted from each transmission antenna is determined so as to be in-phase combined by the base station 102a.
Thus, by transmitting the same spectrum from each antenna at overlapping frequency points, the base station 102a can receive the signal transmitted from the terminal 101a without interference.
Here, in FIG. 12B, the allocation from the seventh to the tenth frequency points in the first transmitting antenna remains. Therefore, as shown in FIG. 12C, the frequency spectrums S ₁ (0) to S ₁ (3) not assigned by the first transmitting antenna are assigned to the seventh to tenth frequency points, respectively.
By assigning in this way, the frequency spectrums S ₁ (4), S ₁ (5), S ₁ (0), S ₁ (1), S ₁ (2), S ₁ (3) are transmitted from the first transmitting antenna. ) And the spectrum are continuously allocated and transmitted to the base station 102a. That is, as shown in FIG. 12C, the spectrum transmitted from the first transmission antenna is obtained by cyclically shifting the spectrum transmitted from the 0th transmission antenna of FIG. 12A by the cyclic shift amount Δ ₁ = 4.

12A to 12C, the case where the number of transmission antennas N _t of the terminal 101a is 2 has been described, but the case where the number of transmission antennas N _t is greater than 2 will be described with reference to FIGS. 13A and 13B.
13A and 13B show examples of transmission spectrums when the number of transmission antennas N _t of the terminal 101a is 5. FIG.

In FIG. 13A, for the 0th transmission antenna (transmission antenna # 0), the transmission frequency spectrums S ₀ (0) to S ₀ (5) are assigned to the frequency points of indexes 8 to 13, and the first transmission antenna (transmission antenna # ₀ ) is assigned. For 1), the transmission frequency spectrum S ₁ (0) to S ₁ (5) is assigned to the frequency points with indices 3 to 8, and for the second transmission antenna (transmission antenna # 2), the transmission frequency spectrum S ₂ (0) To S ₂ (5) are assigned to the frequency points with indices 1 to 6, and for the third transmitting antenna (transmitting antenna # 3), the transmission frequency spectrums S ₃ (0) to S ₃ (5) have indices 6 to 11 assigned to frequency point, the fourth transmit antenna (transmission antenna # 4) transmitted frequency spectrum S ₄ for ₍₀₎ S ₄ (5) is assigned to the frequency point of the index 15-20.

FIG. 13A is an example in the case where cyclic shift in the frequency domain is not performed, and the index of frequency points that can be received without interference is 1, 2, 12, 13, 15 to 20, and is used for 0 and 14 In other frequency indexes, different transmission frequency spectra are transmitted from the transmission antennas # 0 to # 4. Therefore, the base station 102a needs to separate each spectrum.

FIG. 13B shows a transmission spectrum when the above-described cyclic shift is applied to the transmission spectrum of FIG. 13A. In FIG. 13B, the spectrum index i is defined using the frequency index k and the number N _{DFT of} transmission spectrum points (6 points in the example in the figure). In other words, the spectrum index i is defined by

That is, the spectrum index i is the remainder when the frequency index k is divided by the numerical value _NDFT .
Each transmission antenna transmits the frequency spectrum indicated by the spectrum index as shown in FIG. 13B, whereby the same transmission frequency spectrum is transmitted from each transmission antenna at each frequency point. For example, frequency points of frequency indexes 8, 9, 10, 11, 12, and 13 are assigned to the 0th transmission antenna (transmission antenna # 0). Since the frequency indexes 8, 9, 10, 11, 12, and 13 correspond to the spectrum indexes 2, 3, 4, 5, ₀ , and 1, the cyclic shift amount Δ ₀ = 2 is applied to perform cyclic shift. The shifted frequency spectrums S ₀ (2), S ₀ (3), S ₀ (4), S ₀ (5), S ₀ (0), S ₀ (1) are indexed 8, 9, 10, 11, Assign to 12 and 13 frequency points.

In FIG. 13B, the spectrum index is defined on the basis of the frequency index. However, as shown in FIG. 12C, a specific transmission antenna is used as a reference, and the cyclic cyclic shift unit of the transmission antenna has a cyclic shift amount of zero, that is, a cyclic shift. The spectral index may be determined so that no. For example, in the example of FIG. 12C, with reference to the 0th transmission antenna, no cyclic shift is performed in the cyclic shift unit of the 0th transmission antenna (that is, cyclic shift amount Δ ₀ = 0), and the cyclic shift unit of the first transmission antenna does not perform cyclic shift. Control is performed so that a cyclic shift of the shift amount Δ ₁ = 4 is performed.

<Modification>
As shown in FIG. 14, the terminal 101a can be configured such that a predetermined transmission antenna does not have a spectrum cyclic shift unit.
FIG. 14 is a schematic block diagram illustrating a configuration of a terminal 101a1 that is a modification of the present embodiment.
Terminal 101a1 includes encoding section 1401, modulating section 1402, DFT section 1403, precoding section 1404, spectrum cyclic shift sections 1405-1 to 1405N _t -1, mapping sections 1406-0 and 1406-1 to 1406-N _t-. 1, reference signal multiplexers 1407-0, 1407-1 to 1407-N _t -1, OFDM signal generators 1408-0, 1408-1 to 1408-N _t -1, transmitters 1409-0 and 1409-1 1409-N _t -1, transmitting antennas 1410-0, 1410-1 to 910-N _t -1, receiving antenna 1411, receiving unit 1412, control information extracting unit 1413, allocation information acquiring unit 1414, PMI acquiring unit 1415, cyclic A shift amount determination unit 1416 is provided.

Comparing the configuration of the terminal 101a1 in FIG. 14 and the configuration of the terminal 101a in FIG. 9, the former lacks a configuration corresponding to the latter spectral cyclic shift unit 905-0, and in the former, the precoding of the precoding unit 904 is performed. The difference is that the subsequent transmission frequency spectrum is directly output to mapping section 1406-0, but there is no difference in other configurations. This is because, as described above, the cyclic shift unit of the 0th transmission antenna is controlled so that no cyclic shift is performed with the 0th transmission antenna as a reference. Thereby, in this modification, the configuration of the terminal 101b is simplified.

Returning to FIG. 13B, since the frequency allocation of the other transmission antennas in the fourth transmission antenna (transmission antenna # 4) in FIG. 13B does not overlap, if this point is known on the transmission / reception side, cyclic shift by the spectrum index is performed. It does not have to be done.

Next, an example of the configuration of the cyclic shift amount determination unit in FIG. 9 that determines the cyclic shift amount for performing the spectral cyclic shift as shown in FIG. 13B will be described with reference to FIG. Here, a reference numeral 916a is assigned to the cyclic shift amount determination unit described here.
Allocation information in each transmission antenna is input to head frequency index acquisition units 1501-0 to 1501-N _t −1 in cyclic shift amount determination unit 916a. Each head frequency index acquisition unit 1501-0 to 1501-N _t -1 acquires the head (lowest frequency) frequency index of the input allocation information.

For example, in the case of the third transmitting antenna in FIG. 13A, the head frequency index acquisition unit 1501-3 outputs 6 as the head frequency index. The outputs of the head frequency index acquisition units 1501-0 to 1501-N _t −1 are input to modulo arithmetic units 1502-0 to 1502-N _t −1, respectively. The modulo operation unit 1502-0 ~ _1502-N t -1, and outputs the remainder of the top frequency index input divided by _{N DFT.} If the head frequency index input to the modulo arithmetic unit 1502-n is k _{HEAD, n} , the cyclic shift amount Δn output from the modulo arithmetic unit 1502- _n is expressed by the following equation. However, 0 ≦ n ≦ N _t −1.

The output delta _n is the cyclic shift amount in the n spectral cyclic shift section 905-n of the terminal 101a shown in FIG. 9, is output from the cyclic shift amount determining unit 916a.

In this way, the cyclic shift amount determining unit 916a, by calculating the remainder when the first frequency index in the frequency allocation of transmission antennas 910-0 ~ _910-N t -1 terminal 101a divided by _{N DFT,} A cyclic shift amount can be determined.
In the above description, the head frequency index acquisition units 1501-0 to 1501-N _t −1 are based on the 0th frequency point. However, if the terminal 101a and the base station 102a are already known, the head frequency index acquisition units 1501-0 to 1501-N _t −1 are used as the reference. You may output a head frequency index on the basis of a frequency index.
For example, with reference to the 0th transmission antenna in FIG. 13A, the head frequency index output from the head frequency index acquisition unit 1501-0 is 0, and the head frequency index output from the head frequency index acquisition unit 1501-1 is -5. It becomes. In this case, the modulo arithmetic unit 1502-1

Therefore, 1 is output as the cyclic shift amount Δ ₁ . Then, in the first transmission antenna (transmission antenna # 1), the transmission frequency spectrums S ₁ (1), S ₁ (2), S ₁ (3), and S ₁ (S ₁ () as a result of applying the cyclic shift amount Δ ₁ = 1. 4), S ₁ (5), S ₁ (0) are assigned to the frequency points of indexes 3-8.
Here, the time-domain signal waveform by cyclically shifting the spectrum will be described.
The inverse discrete Fourier transform (IDFT) of the transmission frequency spectrum S (m) (0 ≦ m ≦ NDFT-1) is given by the following equation.

IDFT output s of the frequency spectrum given cyclic shift amount Δ _n '(t) is given by the following equation.

In this case the _{N DFT} point IDFT, for any integer m,

Therefore, Formula 22 can be transformed as the following formula.

As described above, the time domain signal s' (t) when the cyclic shift is given is obtained by applying phase rotation to the time domain signal s (t) when the cyclic shift is not given. Even if phase rotation is applied, the peak-to-average power ratio PAPR of the transmission signal is kept at a low value. That is, even if cyclic shift is given, the statistical property of the transmission signal does not change, so that the load on the power amplifier used in the transmission unit of the terminal 101a does not become excessive.

FIG. 16 is a schematic block diagram showing the configuration of the base station 102a in the present embodiment.
The base station 102a includes receiving antennas 1601-0 to 1601-N _r -1, OFDM signal receiving units 1602-0 to 1602-N _r -1, reference signal demultiplexing units 1603-0 to 1603-N _r -1, demapping 1604-0 to 1604-N _r −1, equalization unit 1605, IDFT unit 1606, demodulation unit 1607, decoding unit 1608, propagation path estimation unit 1609, scheduling unit 1610, transmission unit 1611, transmission antenna 1612, PMI determination unit 1613.

Hereinafter, a case will be described in which a signal transmitted from the terminal 101a by single carrier transmission is received using each of the receiving antennas 1601-0 to 1601-N _r −1 of the base station 102a.
In the first embodiment described first, in the case of frequency allocation that causes interference, it is difficult to perform signal separation with one receiving antenna, but in the second embodiment, there is no interference. In order to transmit so as not to occur, the base station has one receiving antenna. However, as an explanation of the present embodiment, for the convenience of generalization when the number of ranks is greater than 1, a plurality of reception antennas are illustrated as reception antennas 1601-0 to 1601-N _r −1.

When the configuration of the base station configuration 102a is compared with the configuration of the base station 102 in the first embodiment (FIG. 5), an extra PMI determination unit 1613 is added in the former, and both of them are the same as the PMI determination unit 1613 and others. The other components and their interconnection relationships are the same except for the connection relationship with the other components. Therefore, the connection relationship between the PMI determination unit 1613 and other components will be described below exclusively.

In this embodiment, since the terminal 101a precodes the transmission signal in the precoding unit 904 according to the propagation path, the scheduling unit 1610 notifies the terminal 101a to the PMI determination unit 513 of the base station 102a. The frequency allocation information of each of the transmission antennas 1409-0 to 1409-N _t −1 and the channel estimation value output by the channel estimation unit 1609 are input.

The PMI determination unit 1613 multiplies the channel estimation value in the frequency allocation input from the scheduling unit 1610 by a plurality of precoding matrices prepared in advance by the PMI determination unit 1613 (for example, in the case of Table 1). The PMI indicating the precoding matrix having the highest SINR (signal-to-interference noise power ratio), SNR (signal-to-noise ratio) or propagation path capacity is output to the transmitter 1611.
The transmission unit 1611 transmits the frequency allocation information input from the scheduling unit 1610 and the precoding matrix indicator (PMI) input from the PMI determination unit 1613 as control information to the terminal 101a via the transmission antenna 1612.

When MU-MIMO (multiuser mimo) that shares time and frequency is performed by a plurality of terminals in FIG. 1 when determining the PMI, the base station on the receiving side takes into account the propagation path of other terminals. Precoding that facilitates signal separation at a station may be performed.
On the other hand, each of the demapping units 1604-0 to 1604 -N _r −1 extracts the received frequency spectrum at the frequency point used for transmission for each spectrum from the received spectrum of the data signal of N _FFT points. Done.

For example, consider the extraction of the transmission frequency spectrum S (1) in the frequency allocation as shown in FIG. 12C. The transmission frequency spectrum S (1) is transmitted from the 0th transmission antenna using the second frequency point, and is transmitted from the first transmission antenna using the eighth frequency point. Accordingly, each of the demapping units 1604-0 to 1604 -N _r −1 extracts the second and eighth frequency points and inputs them to the equalization unit 1605.

The transmission frequency spectrum S (4) is transmitted as S ₀ (4) from the 0th transmission antenna using the fifth frequency point, and S ₁ using the fifth frequency point from the first transmission antenna. Transmission is performed as (4). Accordingly, each of the demapping units 1604-0 to 1604 -N _r −1 extracts only the received signal at the fifth frequency point and inputs it to the equalization unit 1605. Such processing is performed for all _NDFT transmission frequency spectra.

Next, processing performed by the equalization unit 1605 when the assignment illustrated in FIG. 13B is performed will be described.
As an example, a description will be given of the case where the transmission frequency spectrum S (1) is equalized. Assuming that the received signal at the k-th frequency point of the n-th receiving antenna is R _n (k), the received signals R _n (1), R _{n of the} transmission frequency spectrum S (1) input from the demapping unit 1604- _n (7), R _n (13) and R _n (19) are each expressed by the following formula 24.

Here, H _{n, l} (k) is a channel gain at the k-th frequency point between the l-th transmitting antenna and the n-th receiving antenna. Formula 24 is a formula that ignores noise. Since the transmission frequency spectrum S (1) is received at the first, seventh, thirteenth, and nineteenth frequency points, it can be considered that the transmission frequency spectrum S (1) is received with four times the number of reception antennas.

FIG. 17 is a block diagram showing details of the equalization unit 1605.
The equalization unit 1605 includes a combining unit 1701, a weight multiplication unit 1702, a propagation path vector generation unit 1703, and a SIMO weight calculation unit 1704.
For equalizer 1605, is input _{N DFT} × _{N t} pieces of values from the demapping section 1604-0, similarly, from the end of the de-mapping unit _{1604-N r -1 N DFT ×} N t Values are entered. Accordingly, N _DFT × N _t × N _r values are input to the equalization unit 1605 from the demapping units 1604-0 to 1604 -N _r −1.

Therefore, the combining unit 1701 of the equalizing unit 1605 combines the spectrum for each reception frequency point to generate a 4N _r × 1 vector R _{S (1)} . A vector R _{S (1)} input to the weight multiplication unit 1702 by the combining unit 1701 is expressed by the following Expression 25.

In the propagation path vector generation unit 1703, the propagation path estimation value input from the propagation path estimation unit 1609 is expressed by Equation 25.

Is input from the combining unit 1701, and the estimated value of Expression 26 is input to the SIMO weight calculating unit 1704.
Unlike the first embodiment, in this embodiment, since there is no transmission signal that causes interference, a propagation path matrix is not generated, and a propagation path vector (or scalar) is generated.
The SIMO weight calculation unit 1704 multiplies the reception spectrum of the nth reception antenna at the kth frequency point in order to equalize the transmission frequency spectrum S (1), and the SIMO weight vector w _S when there is no interference. ₍₁₎ is calculated. The weight vector w _{S (1)} of 1 × 4N _r (1 row 4N _r column ₎ is expressed by the following Equation 27.

Here, σ ² is the average noise power. That is, the SIMO weight calculation unit 1704 uses the estimated value of the propagation path matrix H _{S (1)} input from the propagation path vector generation unit 1703 and the average noise power estimation value input from the noise estimation unit (not shown _). 27 is calculated, a SIMO weight vector w _{S (1)} is calculated and input to the weight multiplier 1702.
Note that Equation 27 uses MMSE (Minimum Mean Square Error) weights as an example, but ZF (Zero Forcing) weights, MRC (Maximum Ratio Combining) weights, etc. that do not take noise into account. Also good. Furthermore, other signal separation methods such as iterative equalization processing and MLD (Maximum Likelihood Detection) may be used.

In this way, a plurality of frequency points at which the same spectrum is transmitted (in the above example, the transmission frequency spectrum S (1) is transmitted at the first, seventh, thirteenth and nineteenth frequency points) are combined. By generating the weights considered, it is possible to effectively obtain a transmission diversity gain. In addition, since there is no interference, unlike the weight of the first embodiment, any frequency allocation does not involve an inverse matrix operation for calculating the MIMO weight as in Equation 4. Accordingly, the amount of calculation can be reduced and the processing can be performed quickly.
Weight multiplying section 1702 performs multiplication of R _{S (1)} input from combining section 1701 and w _{S (1),} and is S (1) after transmission frequency spectrum equalization.

Is calculated. S (1) after equalization is expressed by the following equation.

As described above, by performing the spectrum cyclic shift in the terminal 101a, the same data can be transmitted without inter-antenna interference even when the assigned frequencies are different among the transmission antennas.
For example, in the case of frequency allocation as shown in FIG. 13B, since the transmission frequency spectrum S (0) is transmitted from three transmission antennas at the sixth frequency point, a transmission antenna diversity effect by precoding for three lines can be obtained. .
Furthermore, since the transmission frequency spectrum S (0) is also transmitted from the 12th and 18th frequency points, a frequency diversity gain can be obtained in addition to the precoding gain.

In addition, when signals of other terminals are multiplexed at some or all of the frequency points used for transmission, that is, in the case of MU-MIMO (multiuser mimo), the description will be given in the first embodiment. As was done, the weights taking into account interference are calculated. Further, it may be a case of single user MIMO in which a terminal transmits two or more layers (stream, rank).

According to the present embodiment, in a system that performs communication with different frequency assignments for each transmission antenna, transmission can be performed without causing inter-antenna interference at each frequency point. Accordingly, since there is no interference from other antennas in the base station 102a, the equalization unit 1605 can perform equalization using a small amount of calculation. Furthermore, transmission diversity by precoding can be used so that transmission signals from the transmission antennas are combined in phase at the reception antenna.
In addition, the base station can perform equalization with high accuracy by generating weights in consideration of the fact that spectra received at various frequencies are combined. Furthermore, since the PAPR characteristic of the transmission signal is maintained in each transmission antenna, the coverage can be expanded.

In the present embodiment, the case where the number of streams to be transmitted (which may be referred to as “independent data”, “rank”, and “layer”) is 1 has been described. When the number of ranks is small, for example, when three streams are transmitted using four transmission antennas, the present embodiment is applied to two antennas that transmit the same signal, and two streams transmitted from the other two antennas are Good transmission can be performed by using a conventional signal separation method in combination.

<Third Embodiment>
In the second embodiment, a case of closed-loop transmission diversity in which precoding is performed based on control information notified from the base station has been described. However, closed-loop transmission diversity cannot be performed when the terminal moves at high speed or when information on the propagation path state (propagation path information itself, precoding matrix indicator PMI, etc.) is not notified from the base station.
Therefore, in the present embodiment, a case where open-loop transmission diversity is applied will be described.

First, STBC (space-time block coding) will be described. Table 2 shows the space-time block coding (also referred to as “Alamuti coding”) when the number of transmission antennas is two.

Here, * represents a complex conjugate operation.

In STBC (space-time block coding), as shown in Table 2, two adjacent data A and B are coded as shown in Table 2 using two adjacent transmission timings of time T and time T + 1, and the terminal Are transmitted redundantly, that is, with redundancy. When applying STBC to SC-FDMA, DFT unit outputs _{N DFT} point frequency spectrum A (m) (0 ≦ m ≦ N DFT -1) and _{N DFT} point frequency spectrum B (m) Space-time block coding is performed using (0 ≦ m ≦ N _DFT −1).

Hereinafter, space-time block coding STBC in SC-FDMA will be described. Further, description will be given with reference to the terminal of the present embodiment denoted by reference numeral 101b and the base station denoted by reference numeral 102b.
FIG. 18 shows an example of the transmission frequency spectrum of the 0th transmission antenna (transmission antenna # 0) and the first transmission antenna (transmission antenna # 1) at time T.
As illustrated in FIG. 18, the terminal 101b transmits different transmission frequency spectra A (m) and B (m) with a frequency allocation that partially overlaps.

That is, at time T, terminal 101b transmits transmission frequency spectrums A (0) to A (5) from the 0th transmission antenna (transmission antenna # 0) by assigning them to the frequency points with indexes 0 to 5, It is assumed that transmission frequency spectrums B (0) to B (5) are assigned to frequency points of indexes 4 to 9 and transmitted from one transmission antenna (transmission antenna # 1). The transmission frequency spectrum transmitted from both transmission antennas partially overlaps at the frequency points of indexes 4 and 5.

Next, FIG. 19A, B, and C show an example of the transmission spectrum of each transmission antenna at the adjacent time T + 1.
It is assumed that the frequency allocation of each transmission antenna is the same as that at time T described above.
FIG. 19A shows frequency allocation when the space-time block coding of Table 2 is applied without applying the frequency cyclic shift when the frequencies partially overlap.
That is, as shown in FIG. 19A, at the adjacent time T + 1, from the 0th transmitting antenna (transmitting antenna # 0), B ^* (0) ˜ B ^* (5) is assigned to the frequency points with indexes 0 to 5 and transmitted, and the first transmission antenna (transmission antenna # 1) sets the conjugate complex number of the transmission frequency spectrum A (0) to A (5) to −1. -A ^* (0) to -A ^* (5) multiplied by are assigned to the frequency points of indexes 4 to 9 and transmitted.

Here, the space-time block coding uses two transmission timings T and T + 1 to separate two different data at the base station. For example, for the fourth frequency point, A ( 4), B (0) is transmitted at time T + 1, B ^* (4), -A ^* (0). As a result, four different transmission frequency spectra are transmitted in duplicate at the two transmission timings, so that it is difficult for the base station to separate them without interference.

Therefore, as shown in FIG. 19B, since A (4) and B (0) are transmitted at time T for the fourth frequency point, B ^* (0) is obtained by space-time block coding at time T + 1. , −A ^* (4) are transmitted from the 0th transmission antenna (transmission antenna # 0) and the first transmission antenna (transmission antenna # 1), respectively. Similarly, at the fifth frequency point, space-time block coding is performed on A (5) and B (1), and at time T + 1, B ^* (1) and −A ^* (5) are transmitted as the 0th transmission. Transmit from the antenna and the first transmitting antenna.
That is, space-time block coding is performed as shown in FIG. 19B. As a result, at the fourth and fifth frequency points, two different transmission frequency spectra are transmitted in duplicate at two transmission timings, so that the base station can separate them.

Here, in FIG. 19B, frequency spectrum allocation is not performed at the 0th to 3rd frequency points of the 0th transmission antenna and the 6th to 9th frequency points of the 1st transmission antenna. In the frequency point which is not allocated in FIG. 19B, since interference from other antennas does not occur, any spectrum may be transmitted. For example, at time T + 1, B (2), B (3), B (4), B (5) are transmitted at the 0th to 3rd frequency points of the 0th transmission antenna (transmission antenna # 0), A (0), A (1), A (2), and A (3) may be transmitted at the sixth to ninth frequency points of the transmission antenna (transmission antenna # 1).
However, in that case, the spectrum transmitted from the 0th and 1st transmission antennas at the 4th and 5th frequency points performs a complex conjugate operation on the original spectrum, and in particular for the 1st transmission antenna, it is multiplied by minus. Therefore, the spectrum at other frequency points is independent from the DFT operation, and when converted to the time domain, the peak-to-average power ratio (PAPR) becomes high. Therefore, as shown in FIG. 19C, even at a frequency point where the assigned frequency does not overlap with other antennas, space-time block coding is performed and transmitted in the same manner as the overlapping frequency point.
By assigning the spectrum so that the spectrum is cyclic as shown in FIG. 19C, the PAPR can be kept low even when space-time block coding is performed.

FIG. 20 shows a specific configuration of the terminal 101b of the present embodiment.
The terminal 101b includes an encoding unit 2001, a modulation unit 2002, a DFT unit 2003, a transmission diversity unit 2004, spectral cyclic shift units 2005-0 and 2005-1, mapping units 2006-0 and 2006-1, and a reference signal multiplexing unit 2007-. 0, 2007-1, OFDM signal generation units 2008-0, 2008-1, transmission units 2009-0, 2009-1, transmission antennas 2010-0, 2010-1, reception antenna 2011, reception unit 2012, control information extraction unit 2013, the allocation information acquisition part 2014, and the cyclic shift amount determination part 2015 are comprised.

Hereinafter, a case will be described in which the same data is transmitted by single carrier transmission with different frequency allocations using each of the transmission antennas 2010-0 and 2010-1 of the terminal 101b.
In this embodiment, description will be made using space-time block coding as open-loop transmission diversity, but it can also be applied to other open-loop transmission diversity, for example, spatial frequency block coding SFBC and cyclic delay diversity CDD. .

The number N _t of transmission antennas of the terminal 101b is assumed to be 2.
Comparing the configuration of the terminal 101b and the configuration of the mobile station configuration 101a of the second embodiment (FIG. 9), the latter precoding unit 904 is the transmission diversity unit 2004 in the former, and the latter PMI acquisition unit 913 is The former is lacking. In terms of both functions, since open-loop transmission diversity does not require propagation path information, the terminal 101b can perform transmission diversity without notification information from the base station 102b. In this respect, the second embodiment Is different.

Since the processing from the encoding unit 2001 to the DFT unit 2003 of this embodiment is the same as that of the first and second embodiments, the description thereof is incorporated. The output of the DFT unit 2003 is input to the transmission diversity unit 2004 for each two SC-FDMA signals.
The transmission diversity unit 2004 performs space-time block coding on the two SC-FDMA transmission frequency spectra A (m) and B (m) based on the following Table 3, and the spectral cyclic shift unit 2005-0 , 2005-1.

FIG. 21 is a block diagram illustrating details of the cyclic shift amount determination unit 2015.
Cyclic shift amount determination unit 2015 includes head frequency index acquisition units 2101-0 to 2101-1, subtraction units 2102-0 and 2102-1, modulo arithmetic units 2103-0 to 2103-1, and switching units 2104-0 to 2104. 1 is provided.
The frequency allocation information of each of the transmission antennas 2010-0 and 2010-1 is input from the allocation information acquisition unit 2014 to the head frequency index acquisition units 2101-0 to 2101-1. Starting frequency index acquisition sections 2101-0 to 2101-1 acquire the starting (lowest frequency) frequency index of the frequency allocation of each transmitting antenna from the input allocation information.

For example, in the frequency allocation in FIGS. 18 and 19A to 19C, in the case of the 0th transmitting antenna 2010-0, the head frequency index acquisition unit 2101-0 outputs “0” as the head frequency index k _{HEAD, 0.} In the case of the first transmitting antenna 2010-1, the head frequency index acquisition unit 2101-1 outputs “4” as the head frequency index k _{HEAD, 1} .

The outputs k _{HEAD, 0} and k _{HEAD, 1} of each head frequency index acquisition unit 2101-0 to 2101-1 are input to two subtraction units 2102-0 and 2102-1. Each subtraction unit 2102-0, 2102-1 subtracts the output of the other head frequency index acquisition unit from the output of the corresponding head frequency index acquisition unit 2101-0 to 2101-1 so that k _{dif, 0} , kdif _{, 1} is calculated and output to the modulo arithmetic units 2103-0 and 2103-1. For example, in the subtraction unit 2102-0,

And “−4” is input to the modulo arithmetic unit 2103-0 as the difference value k _{dif, 0} . On the other hand, in the subtraction unit 2102-1,

And “4” is input to the modulo arithmetic unit 2103-1 as the difference value k _{dif, 1} .
Then the modulo operation unit 2103-0,2103-1, and outputs the remainder of the input the difference value divided by _{N DFT. Assuming} that the input leading frequency index is k _{dif, n} , the output Δn of the modulo arithmetic unit 2103- _n is expressed by the following equation. However, n = 0 and 1.

Delta _n is input to the switching unit 2104-n. Although cyclic shift amount delta _n is calculated in modulo operation unit 2103-n, as shown in FIG. 18, it not performed cyclic shift at time T. Therefore, the switching unit in FIG. 21 determines whether the current signal processing is time T or time T + 1 in space-time block coding, and if time T, outputs Δ _n = 0, if the time T + 1 the input from the modulo operation unit as the amount of cyclic shift delta _n, and outputs the cyclic shift amount determining unit.
For example, in the case of frequency allocation in FIG. 18, the subtraction unit 2102-0 in FIG. 21 has k _{dif, 0} = −4, N _DFT = 6,

Because it is, and outputs 2 as the cyclic shift amount delta _0. On the other hand, the subtractor 2102-1 in FIG. 21 has k _{dif, 1} = 4 and N _DFT = 6,

Therefore, 4 is output as the cyclic shift amount Δ ₁ .
As described above, by determining the cyclic shift amount, the cyclic shift as shown in FIG. 19C can be performed.
Thus, the cyclic shift amount determining unit 2015 calculates the difference between the first frequency index in the frequency assignment of each transmit antenna _{2010-0,2010-1,} by calculating the remainder when divided by _{N DFT,} a cyclic The amount of shift can be determined.

In FIGS. 18 and 19A to 19C, a cyclic shift is applied to a signal transmitted at time T + 1 without applying a cyclic shift at time T. However, since the cyclic shift is relative, time T A cyclic shift may be applied to the signal transmitted at time T1, and a cyclic shift may not be applied to the signal transmitted at time T + 1, or a cyclic shift may be applied at both times.

The configuration of the terminal 101b in FIG. 20 is the same as the configuration of the terminal in FIG. 9 of the second embodiment except for the above, and performs predetermined signal processing to transmit a signal from each transmission antenna.
The signal transmitted from the terminal 101b is received by the receiving antenna of the base station 102b via the wireless propagation path.
In the first embodiment, in the case of frequency allocation that causes interference, signal separation is difficult with one receiving antenna. However, in this embodiment, transmission is performed so that interference does not occur. As with the configuration, a single receiving antenna may be used.

FIG. 22 is a block diagram showing a specific configuration of the base station 102b.
The base station 102b may receive antennas _{2201-0 ~ 2201-N r -1,} OFDM signal receiving unit 2202-0 ~ _2202-N r -1, the reference signal separating unit 2203-0 ~ _2203-N r -1, demapping Sections 2204-0 to 2204-N _r −1, an equalization section 2205, an IDFT section 2206, a demodulation section 2207, a decoding section 2208, a propagation path estimation section 2209, a scheduling section 2210, a transmission section 2211, and a transmission antenna 2212.

Hereinafter, a case will be described in which a signal transmitted from the terminal 101b by single carrier transmission is received using each of the receiving antennas 2201-0 to 2201-N _r −1 of the base station 102b.
When the configuration of the base station 102b of the present embodiment is compared with the configuration of the base station 102 of the first embodiment (FIG. 5), the configuration of the former equalization unit 2205 is different from that of the latter equalization unit 505. However, the other configuration is the same.

In each of the demapping units 2204-0 to 2204-N _r -1, the received spectrum at the frequency point used for transmission is extracted for each spectrum from the received spectrum of the data signal of N _FFT points.
For example, it is assumed that the transmission frequency spectrum A (4) is extracted when the transmission is performed with the frequency allocation as shown in FIG. 18 at time T and the transmission is performed with the frequency allocation as shown in FIG. 19C at time T + 1. Transmission frequency spectrum A (4) is transmitted from the 0th transmission antenna at time T and from the first transmission antenna at time T + 1, both using the fourth frequency point.
Accordingly, each demapping unit 2204-0 to 2204-N _r −1 extracts two frequency signals of the fourth frequency point at time T and time T + 1 and inputs them to the equalization unit 2205. If the received signal at the k-th frequency point of the n-th receiving antenna at time t is R _{n, t} (k), and there is no time variation of the propagation path in the two SC-FDMA symbols that perform space-time block coding, The signals R _{n, T} (4) and R _{n, T + 1} (4) received by A (4) input from the demapping units 2204-0 to 2204-N _r −1 to the equalization unit 2205 are respectively This is expressed by Equation 37.

The above two reception frequency signals are input to the equalization unit 2205.

On the other hand, a spectrum transmitted at a non-overlapping frequency, for example, B (3), is transmitted at the time T using the seventh frequency point of the first transmitting antenna, and from the 0th transmitting antenna at the time T + 1. Transmission is performed using the first frequency point. Therefore, each demapping unit extracts two frequency signals of the seventh frequency point at time T and the first frequency point at time T + 1, and inputs them to the equalization unit. If the received signal at the k-th frequency point of the n-th receiving antenna at time t is R _{n, t} (k), and there is no time variation of the propagation path in the two SC-FDMA symbols that perform space-time block coding, Signals R _{n, T} (7) and R _{n, T + 1} (1) received by B (3) input from the demapping unit to the equalization unit are expressed by the following Expression 36, respectively.

Such processing is performed for all _NDFT transmission frequency spectra.

Next, signal processing in the equalization unit 2205 in FIG. 22 will be described with reference to FIG.
FIG. 23 is a schematic block diagram showing the configuration of the equalization unit 2205.
The equalization unit 2205 includes reception antenna equalization units 2301-0 to 2301-N _r −1, a reception antenna combining unit 2302, and a weighting unit 2303.

The output of the demapping unit 2204-n is input to the receiving antenna equalization unit 2301-n of the equalization unit 2205. Receiving antenna equalization section 2301-n performs equalization processing for each of receiving antennas 2201-0 to 2201-N _r −1 using the propagation path estimation value input from propagation path estimation section 2209 in FIG. The data is input to the receiving antenna combining unit 2302.
Processing in the reception antenna equalization unit 2301-n will be described later.

The outputs of the reception antenna equalization units 2301-0 to 2301-N _r −1 input to the reception antenna combining unit 2302 are combined by the reception antenna combining unit 2302 to obtain the reception antenna diversity effect, and Are input to the weighting unit 2303.
Weighting unit respectively _{N DFT} pieces of A (m) and _{N DFT} pieces of the resulting 2303 B (m) is, as each synthesized in suitable proportions, performs weighting for each spectrum. For example, when A (m) is weighted according to the MMSE standard, the weight of the following equation is multiplied by the input.

Here, σ ² of the denominator is the average noise power, and the denominator indicates that the power of the propagation path in which A (m) is transmitted is totaled and the average noise power is added as a whole. A specific example will be described later.
A signal weighted for each spectrum is input to the IDFT unit 2206 of FIG. 22 as an output of the equalization unit 2205.

Here, the signal processing in the reception antenna equalization unit 2301-n will be described with reference to FIG.
FIG. 24 is a schematic diagram showing a configuration of the receiving antenna equalization unit 2301-n.
Receiving antenna equalization section 2301-n includes weight multiplication sections 2401-0 to 2401-N _r −1, weight calculation section 2402, complex conjugate section 2403, negative multiplication section 2404, and combining section 2405.

The two signals input from the demapping unit 2104-n are input to the weight multiplication units 2401-0 to 2401-1, respectively.
Weight multiplying sections 2401-0 to 2401-1 multiply the signal input from demapping section 2104-n and the signal input from weight calculating section 2402, and perform output.

Next, the weight calculation unit 2402 will be described. The weight calculation unit 2402 calculates a weight using the input propagation path estimation value. The weight w _{n, l} (k) for the l-th transmitting antenna to be multiplied by the reception spectrum of the n-th receiving antenna at the k-th frequency point is expressed by the following Equation 38.

Here, H ^* _{n, l} (k) represents the complex conjugate of the propagation path gain between the l-th transmitting antenna and the n-th receiving antenna at the k-th frequency point.
The weight calculation unit 2402 inputs the weight for the 0th transmission antenna and the weight for the first transmission antenna to the weight multiplication units 2401-0 to 2401-1, respectively.

The output of the weight multiplier 2401-0 is input to the synthesizer 2405. On the other hand, the output of the weight multiplication unit 2401-1 is input to the complex conjugate unit 2403. The complex conjugate unit 2403 performs a complex conjugate operation on the input signal and inputs it to the negative multiplication unit 2404.
In the case of equalization of A (m), the negative multiplication unit 2404 multiplies the input signal by a negative sign (minus) and outputs the result to the synthesis unit. Further, when equalizing B (m), it is directly input to the synthesis unit 2304. The synthesizer 2304 synthesizes the signals transmitted from the transmitting antennas by synthesizing the two input signals.

The combining unit 2405 performs a combining process on all A (m) and B (m) (0 ≦ m ≦ N _DFT −1), and receives the received antenna combining unit 2302 as an output of the receiving antenna equalizing unit 2301-n. To enter.
Here, with reference to A (4) and B (3) as an example, signal processing of the reception antenna equalization unit 2301-n will be described.

In the case of equalization of A (4), the outputs of the weight multipliers 2401-0 and 2401-1 are expressed as follows.

Next, since the complex conjugate operation is performed in the complex conjugate unit 2403 for the output of the weight multiplication unit 2401-1, the above equation is expressed as follows.

In the combining unit 2405 to which the two signals are input, the two signals are combined.
Since the spectrum to be extracted now is A (m) instead of B (m), the second signal (output of the complex conjugate unit 2303) is multiplied by minus and combined. That is A (4) after equalization

Is expressed by the following equation.

Here, the weight w _{A (4)} multiplied by the weighting unit 2303 in FIG. 23 corresponding to A (4) after equalization in this case is based on Expression 37.

It becomes.
As described above, the information regarding B (0) included in the received signal is canceled by combining the two received signals, and only A (4) which is a desired spectrum can be extracted. Similarly, B (0) can be taken out.

Next, the equalization of B (3) will be described.
In the case of equalization of B (3), the outputs of the weight multipliers 2401-0 to 2401-1 are expressed as follows, respectively.

Next, since the complex conjugate operation is performed by the complex conjugate unit 2303 on the output of the weight multiplication unit 2301-1, the above equation is expressed as follows.

In the synthesizing unit 2405 to which the above two signals are input, the two signals are synthesized. Since the spectrum extracted now is not B (m) but A (m), the second signal is synthesized without being multiplied by minus. That is, B (3) after equalization

Is represented by the following equation.

Here, the weight w _{B (3)} multiplied by the weighting unit 2303 in FIG. 23 corresponding to B (3) in this case is based on Expression 37.

It becomes.

In this way, even for transmission frequency spectra whose assignments do not overlap, it is possible to synthesize spectra received at different frequency points by performing the same processing as when the spectra overlap, thus obtaining good transmission characteristics. Can do.

In the present embodiment, the case where transmission diversity that does not use propagation path information is applied to a system that performs transmission using different bands for each antenna has been described. When performing open-loop transmission diversity in this way, it is possible to prevent interference from occurring at the base station by performing transmission with an appropriate cyclic shift according to the assigned frequency at each transmission antenna. It is possible to perform good transmission. Although the description has been given using space-time block coding as transmission diversity that does not use propagation path information, other developments such as SFBC that performs Alamouti coding on the frequency axis and CDD that cyclically shifts time signals are used. Of course, it can also be applied to loop transmit antenna diversity. Furthermore, it is also possible to apply the precoding described in the second embodiment to this embodiment, that is, it is possible to use closed loop transmission diversity such as space-time block coding and closed loop transmission diversity such as precoding together. . Further, although the case where the number of streams (independent data, rank, layer) to be transmitted is 1 has been described, the present embodiment can also be applied to communication with two or more ranks using transmission diversity.

The various functions described in the above-described embodiments relating to the present invention can be replaced by execution of a computer program for controlling the central processing unit CPU or the like in a built-in microcomputer. Information handled by these devices is temporarily stored in the storage device RAM during the processing, stored in various recording device ROMs and magnetic storage devices HDD, read out by the CPU as necessary, and corrected / written. Is done. As a recording medium for storing the program, a semiconductor medium (for example, ROM, nonvolatile memory card, etc.), an optical recording medium (for example, DVD, MO, MD, CD, BD, etc.), a magnetic recording medium (for example, magnetic tape, Any of a flexible disk etc. may be sufficient. In addition, by executing the stored program, not only the functions of the above-described embodiment are realized, but also based on the instructions of the program, the processing is performed jointly with the operating system or other application programs, etc. The functions of the above embodiments of the invention can also be realized.
In addition, a computer program capable of executing the various functions described in the above-described embodiment relating to the present invention can be stored in a portable recording medium and distributed as an independent product in the market, or the Internet. Or can be distributed to the market by transferring to a server computer connected via a network. In this case, the recording medium and the storage device of the server computer also conflict with the technical scope of the claims of the present invention.
Also, some or all of the terminals and base stations in the above-described embodiments may be realized as an LSI that is typically a semiconductor integrated circuit. Each functional block of the terminal and the base station may be individually formed as a semiconductor chip, or a part or all of them may be integrated into a chip.
Further, the method of circuit integration is not limited to LSI, and may be realized by a dedicated circuit or a general-purpose processor.
The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to the present embodiment, and the design and the like within the scope not departing from the gist of the present invention are also claimed. Included in the range.

The present invention can be used in the fields of mobile radio communication and fixed radio communication using transmission diversity.

DESCRIPTION OF SYMBOLS 101 ... Terminal 102 ... Base station 201 ... Encoding part 202 ... Modulation part 203 ... DFT part 204 ... Copy part 205 ... Mapping part 206 ... Reference signal multiplexing Unit 207 ... OFDM signal generation unit 208 ... transmission unit 209 ... transmission antenna 210 ... reception antenna 211 ... reception unit 212 ... control information extraction unit 213 ... allocation information acquisition unit 501 ... Receiving antenna 502 ... OFDM signal receiving unit 503 ... Reference signal separating unit 504 ... Demapping unit 505 ... Equalizing unit 506 ... IDFT unit 507 ... Demodulating unit 508 ... Decoding unit 509 ... propagation path estimation unit 510 ... scheduling unit 511 ... transmission unit 512 ... transmission antenna 9 DESCRIPTION OF SYMBOLS 1 ... Coding part 902 ... Modulation part 903 ... DFT part 904 ... Precoding part 905 ... Spectral cyclic shift part 906 ... Mapping part 907 ... Reference signal multiplexing part 908 ... OFDM signal generation unit 909 ... transmission unit 910 ... transmission antenna 911 ... reception antenna 912 ... reception unit 913 ... control information extraction unit 914 ... allocation information acquisition unit 915 ... -PMI acquisition unit 1601 ... receiving antenna 1602 ... OFDM signal receiving unit 1603 ... reference signal separation unit 1604 ... demapping unit 1605 ... equalization unit 1606 ... IDFT unit 1607 ... Demodulation unit 1608 ... Decoding unit 1609 ... Propagation path estimation unit 1610 ... Scheduling unit 611 ... Transmission unit 1612 ... Transmission antenna 1613 ... PMI decision unit 2001 ... Encoding unit 202 ... Modulation unit 2003 ... DFT unit 2004 ... Transmission diversity unit 2005 ... Spectrum Cyclic shift unit 2006 ... mapping unit 2007 ... reference signal multiplexing unit 2008 ... OFDM signal generation unit 2009 ... transmission unit 2010 ... transmission antenna 2011 ... reception antenna 2012 ... reception unit 2013 ... Control information extraction unit 2014 ... Allocation information acquisition unit 2015 ... Cyclic shift amount determination unit 2201 ... Receiving antenna 2202 ... OFDM signal receiving unit 2203 ... Reference signal separation unit 2204 ... Demapper 2205 ... Equalizer 2206 ... I DFT unit 2207 ... demodulation unit 2208 ... decoding unit 2209 ... propagation path estimation unit 2210 ... scheduling unit 2211 ... transmission unit 2212 ... transmission antenna

Claims (19)

1. Each of a plurality of sets of data signal sequences related to the same data signal sequence is at least partly a plurality of mapping units input via a spectrum cyclic shift unit, and the input data signal sequences are A plurality of mapping units arranged above and outputting the arranged data signal sequence as a transmission frequency spectrum;
   An allocation information acquisition unit that controls the plurality of mapping units based on allocation information to arrange the data signal sequence on the frequency axis, and controls the data signal sequences so that they partially overlap;
   A cyclic shift amount determination unit that determines a cyclic shift amount based on the control of the allocation information acquisition unit;
   The spectrum cyclic shift unit shifts the input data signal sequence by the cyclic shift amount under the control of the shift amount determination unit, and outputs the partially overlapped data signals to be the same. To do
   A plurality of transmission antennas for transmitting a transmission frequency spectrum output from the plurality of mapping units at a radio frequency;
   A communication apparatus comprising:
2. The communication apparatus according to claim 1, wherein all of the plurality of sets of data signal sequences are input to the mapping unit via a spectrum cyclic shift unit.
3. A precoding unit that changes the amplitude, phase, or both of the data signal of the data signal sequence and inputs the data signal sequence directly to the mapping unit or to the mapping unit via the spectral cyclic shift unit The communication apparatus according to claim 1, further comprising:
4. The said spectrum cyclic shift part performs cyclic shift on the basis of the said transmission frequency spectrum arrangement | positioning in the specific thing of these transmission antennas, The Claim 1 characterized by the above-mentioned. Communication device.
5. The communication apparatus according to any one of claims 1 to 3, wherein the spectrum cyclic shift unit performs cyclic shift based on an index of the transmission frequency spectrum.
6. The first communication device according to claim 1 or 2,
   One or more receive antennas;
   For each transmission frequency spectrum from the receiving antenna, an equalization unit that performs equalization using SIMO weights when there is no interference,
   A second communication device comprising:
   Comprising
   A communication system, wherein data signals are transmitted and received between the first communication device and the second communication device.
7. Prepare multiple sets of data signal sequences related to the same data signal sequence,
   Changing the amplitude, phase or both of the data signal for each of the plurality of sets of data signal series;
   A cyclic shift is performed on the plurality of changed data signal sequences,
   A plurality of sets of data signal sequences subjected to the cyclic shift are arranged on the frequency axis, and at that time, a part of the plurality of sets of data signal sequences is overlapped, and the overlapping data signals are the same,
   Transmitting a plurality of sets of transmission frequency spectra arranged on the frequency axis at a radio frequency from a plurality of transmission antennas;
   A communication method characterized by the above.
8. Arranging a plurality of data signal sequences on a plurality of first transmission subcarriers in a specific symbol;
   The plurality of second transmission subcarriers in the symbol have the same data signal sequence as the plurality of data signals, and the plurality of first transmission subcarriers and the plurality of second transmission subcarriers partially overlap. Arranged to
   The plurality of first transmission subcarriers such that the same data signal is arranged in each of the plurality of subcarriers in which the first transmission subcarrier and the second transmission subcarrier partially overlap. A plurality of data signal sequences arranged in the plurality of data signal sequences arranged in the plurality of second transmission subcarriers, or both are cyclically shifted,
   Next, a plurality of data signal sequences arranged on the first transmission subcarrier are transmitted from a first transmission antenna, and a plurality of data signal sequences arranged on the second transmission subcarrier are transmitted from a second transmission antenna. To
   A communication method characterized by the above.
9. The communication method according to claim 8, wherein the first transmission antenna and the second transmission antenna are provided in a single transmission device.
10. The communication method according to claim 8, wherein the first transmission antenna is provided in one transmission device, and the second transmission antenna is provided in another transmission device.
11. The wireless communication method according to claim 9 or 10, wherein the plurality of data signals are subjected to precoding for changing amplitude, phase, or both.
12. A plurality of mapping units for arranging a plurality of sets of data signal sequences related to the same data signal sequence on the frequency axis, and outputting the arranged data signal sequences as a transmission frequency spectrum;
    An allocation information acquisition unit that controls the plurality of mapping units based on allocation information to arrange the data signal sequence on the frequency axis, and controls the same, separated, or partially overlapping;
    A plurality of transmission antennas for transmitting a transmission frequency spectrum output from the plurality of mapping units at a radio frequency;
    A communication apparatus comprising:
13. One or more receive antennas;
    For each transmission frequency spectrum from the receiving antenna, an equalization unit that performs equalization using a SIMO weight when there is no interference and a MIMO weight when there is interference;
    A communication apparatus comprising:
14. A first communication device according to claim 12 and a second communication device according to claim 13, wherein data signals are transmitted and received between the first communication device and the second communication device. The communication system characterized by performing.
15. Prepare multiple sets of data signal sequences related to the same data signal sequence,
    The plurality of sets of data signal sequences are arranged on the frequency axis, and at that time, the plurality of sets of data signal sequences are made the same, separated or partially overlapped,
    A communication method, comprising: transmitting a plurality of sets of transmission frequency spectra arranged on the frequency axis at a radio frequency from a plurality of transmission antennas.
16. Receiving multiple transmit frequency spectra from one or more receive antennas;
    For each transmission frequency spectrum, when there is no interference, the weight in that case is used, and when there is interference, the weight in that case is used for equalization to restore the transmission frequency spectrum.
    A communication method characterized by the above.
17. A transmission diversity unit that applies coding belonging to open-loop diversity such as space-time block coding, space-frequency block coding, cyclic delay diversity, etc. to a plurality of sets of data signal sequences;
    A plurality of spectral cyclic shift units that cyclically shift a plurality of data signal sequences output by the transmission diversity unit;
    A plurality of data signal sequences that are outputs of the plurality of spectrum cyclic shift units are arranged on the frequency axis so as to partially overlap, and a plurality of mapping units that output the arranged data signal sequences as transmission frequency spectrums;
    A plurality of transmission antennas that transmit the transmission frequency spectrum output from the plurality of mapping units sequentially at radio frequencies in two adjacent times;
    A communication apparatus comprising:
18. The plurality of sets of data signal sequences output from the transmission diversity unit are a first data signal sequence and a second data signal sequence, and the signals are conjugate complex numbers of signals of the first signal sequence. A second data sequence, a third data signal sequence different from the first data signal sequence, and a fourth data signal sequence, the signal being a conjugate complex number of the signal of the third data signal sequence The communication apparatus according to claim 17, comprising a fourth data signal sequence obtained by multiplying a negative sign.
19. Multiple receive antennas;
    An equalization unit that performs equalization for each transmission frequency spectrum from the receiving antenna, a weight calculation unit that calculates a weight used for equalization, a complex conjugate unit that selectively performs a conjugate complex operation, and a selective An equalization unit comprising a negative multiplication unit for performing negative multiplication on
    A communication apparatus comprising:

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